Method for maintaining channels and a subscriber station for use in an ISDN system

Abstract

A method and at least one subscriber station utilizes a software package in combination with at least one terminal adapter which links isdn circuit-switched channels, such as "B", "H0", "H10", "H11" and the like, into a single logical connection and synchronizes the linked channels in an isdn system. The station allows a subscriber to dynamically select various bandwidths (i.e. different channels) for data transfer, such as text or graphics. The software package and, preferably, multiple terminal adapters, reside on a personal computer and also permits simultaneous messaging and voice functions between several such subscriber stations. Any number of logical channels can be managed. isdn data is segmented based on the channel's respective data rates and thereafter simultaneously sent on the channels of the logical connection. isdn data is consequently transferred at a rate greater than the rate available on any single isdn channel.

Description

TECHNICAL FIELD

This invention relates to methods and subscriber stations for use in ISDN systems and, in particular, to methods and subscriber stations for logically combining ISDN circuit-switched channels to provide relatively high speed communication between several such subscriber stations.

BACKGROUND ART

It is desirable to achieve high speed data transfer over circuit-switched channels at a rate above the rate available on any one circuit-switched channel. Although the capability currently exists, solutions have been costly.

An existing hardware solution is illustrated in FIG. 1. This method requires one or more external terminal adapters, a multiplexer, cabling, and a sync board for a PC. The system's cost is directly proportional to the available bandwidth.

Additionally, U.S. Pat. No. 4,387,271, issued to Artom, discloses a combined telephone and data-transfer system. The system makes use of common data network and data retrieval units to effect transmission of data on subscriber lines at frequencies outside the voice band. The data is divided into groups which are preceded by an address code.

U.S. Pat. No. 4,688,168, issued to Gudaitis et al., discloses a high speed data transfer method and apparatus. The apparatus includes a bus master controller which sequences through source and destination addresses at a rate greater than the connected units' ability to transfer data, thereby enhancing the speed of data transmission. The high speed data bus includes separate data transfer and master control bus portions.

U.S. Pat. No. 4,827,409, issued to Dickson, discloses a high speed interconnect unit for a digital data processing system. The interconnect unit includes a bus for transferring both control and user information between the unit and an external device. A simplified protocol accommodates "stalls" between the communicating devices during transfer.

U.S. Pat. No. 4,866,703, issued to Black et al., discloses an ISDN module having a time division multiplexed (TDM) switching network. Facility interface cards connect subscribers to the TDM network and provide for two-wire and four-wire subscriber connections, T1 line connections and three port conferencing arrangements. Subsystems are connected by an Ethernet LAN, allowing the system to provide both Primary Rate and Basic Rate Interfaces to subscribers.

U.S. Statutory Invention H586, issued to Kun, discloses an ISDN D-Channel handler. The ISDN network utilizes TDM and the handler, in an exchange termination (ET) collects and distributes D-channel data to various subscriber lines. A translator accesses the data and passes supervisory and signalling information contained therein to a central processor in the ET. This information is then formatted according to the International Telegraph and Telephone Consultative Communication (CCITT) standard and transmitted to the intended subscriber on the appropriate D-channel.

U.S. Pat. No. 4,878,216, issued to Yunoki, discloses a method for the management of logical channels for ISDN packet service between and ISDN and subscribers. The method allocates a logical channel group number (LCGN) in the ISDN in advance for each piece of data terminal equipment in a subscriber station. The terminal equipments notifies the ISDN of the LCGN, enabling the ISDN to offer communication service without separate management of the each piece of data terminal equipment at each subscriber site.

U.S. Pat. No. 4,914,574, issued to Terada et al., discloses a data transmission apparatus having cascaded data processing modules for daisy chain data transferring. The apparatus utilizes a plurality of data processing modules, each functional as a computer. Required sequence setting of the input/output ports of each module is performed by a port sequencer. The daisy chain transfer of the selective, load distribution and collective data transfers is combined between the data processing modules, thereby resulting in a high speed and efficient data transmission.

U.S. Pat. No. 4,937,734, issued to Bechtolsheim, discloses a high speed bus with a virtual memory data transfer and rerun cycle capability. A virtual memory scheme allows high speed data transfer, minimizing the number of lines required to implement the bus. The idle time of a particular device is also minimized.

U.S. Pat. No. 4,970,723, issued to Lin, discloses an ISDN basic rate interface (BRI) arranged for quad voice operation. The ISDN BR is interposed between a switch and a plurality of voice or data terminals, thereby enabling at least three voice terminals (or a data terminal and two voice terminals) to operate simultaneously through the B-channels of the BRI to the switch. To allow for the service, voice samples are digitized by a code converter.

U.S. Pat. No. 4,985,891, issued to Fujiwara et al., discloses an ISDN system having a subscriber line multiplexer with means for reducing the load on an ISDN switch by establishing different data links through D-channels on the subscriber line. The multiplexer comprises subscriber interfaces connected to digital subscriber lines (DSLs) and statistically multiplexes a plurality of signals for Link Access Procedure on D-channels (LAPDs) to form an additional data link between each subscriber interface and the ISDN switch, thereby reducing the load on the ISDN switch.

SUMMARY OF THE INVENTION

The present invention will provide a plurality of services to the user for performing various communication tasks over ISDN lines. These services include high speed data (file, text, graphics, etc.) transferring, messaging, and voice functions. Additionally, the invention utilizes a windowed interface and allows for these services to be active simultaneously.

It is therefore an object of the present invention to provide a method and at least one subscriber station in an ISDN system for logically combining ISDN circuit-switched channels to achieve a relatively high speed data transfer rate in a cost efficient fashion.

It is a further object of the present invention to provide a method and at least one subscriber station in an ISDN system for logically combining ISDN circuit-switched channels to achieve a data transfer rate greater than the rate available on any single ISDN channel.

It is yet another object of the present invention to provide a method and at least one subscriber station in an ISDN system for logically combining ISDN circuit-switched channels to achieve file transfer, messaging and voice communication capabilities.

It is still another object of the invention that while a data connection exists, either side will be able to send messages to the other side. Additionally, each side has an area where messages will appear as they are received.

In carrying out the above objects and other objects of the present invention, a method for maintaining a plurality of ISDN circuit-switched channels in an ISDN is provided. The ISDN is used for performing various communication tasks including transferring data between subscriber stations. Each of the channels has a known bandwidth. At least one of the subscriber stations includes a computer having an internal bus and at least one terminal adapter (TA) for coupling the channels to the internal bus. The method includes the steps of linking several of the plurality of channels into a single logical connection, and synchronizing the channels of the single logical connection to permit the data to be transferred to a second subscriber station at a first rate greater than the rate available on any one of the linked ISDN circuit-switched channels.

In further carrying out the above objects and other objects of the present invention, subscriber stations are provided in an ISDN system. The ISDN system performs various communication tasks including transferring data between subscriber stations over a plurality of ISDN circuit-switched channels. Each of the channels has a known bandwidth. At least one of the subscriber stations includes a computer having an internal bus and at least one terminal adapter for coupling the channels to the internal bus. The at least one subscriber station also includes link means associated with the computer for linking several of the plurality of channels into a single logical connection and synchronizing means associated with the computer for synchronizing the channels of the single logical connection to permit the data to be transferred between the first and second stations at a rate greater than the rate available on any one of the linked ISDN circuit-switched channels.

Preferably, the data appears to a user to be transferred as a single bit stream on a computer over ISDN lines to achieve data rates greater than the rate available on any single circuit-switched ISDN channel.

Also preferably, the method and subscriber stations utilize a high speed data transfer (HSDT) software package that resides on a computer that links and synchronizes ISDN circuit-switched channels of similar and dissimilar data rates some or all of which exist on multiple ISDN channels. A subscriber has the flexibility to select various bandwidths in a dynamic fashion for data rate transfer with independent voice grade capability.

The HSDT software package may exist as source code or object code found in an object library or an executable file on any general purpose computer. Preferably, a subscriber provides information through software function calls. Multiple physical ISDN circuit-switched channels are maintained to appear as a single logical connection. The software package segments user data to match various data rates to be sent simultaneously on each physical channel. Any number of logical channels are maintained (up to the number of available channels).

The software package includes a software interface to internal ISDN TA's (i.e. TA's that provide data transfer capability on Circuit Switched Channels and `D` type packet switched channels to the general purpose computer's internal bus) and a list of phone numbers and rate adaptation capabilities on a per channel basis.

On a per logical connection basis, the software package includes (1) a reference to an area in memory to receive data; (2) requested bandwidth by specifying a list of rate adaptations to be assigned to this single logical connection; and (3) a phone number (ISDN address) of a remote process.

Preferably, the HSDT software package performs the following steps to establish the single logical connection: (1) matches each given rate adaptation with an available channel; (2) sends the rate adaptation list to the remote process using the given phone number (or ISDN address), and phone number to dial back; (3) the remote process delivers this list to the user of the software; (4) allows the subscriber to modify the rate adaptations and/or eliminate some, and presents this list back to the software package; (5) matches this new list to available compatible channels; (6) sends back the modified list along with phone numbers for each channel; (7) each channel is dialed up in order to make the physical connection using the new rate adaptation list; and (8) once all the channels in the list are established as physical connections, the subscriber is given a `handle` on this one logical connection.

The HSDT software package also preferably initiates receives of data (pending requests) to allow the remote process to send data at any time, simultaneous on all channels at their respective data rates. The locations for receives are references to segments of varying length based on each circuit-switched channel's data rate.

The software package also allows data to be sent over the logical connection by providing: (1) reference in memory to a contiguous block of data to be sent; and (2) length of data to send.

In preparing to send data, the software package breaks data up into segments of varying length, one for each physical channel. The length is proportional to each channel's data rate. In segmenting the data, the following preferably occurs: (1) a request is made to send a block of data; (2) the block is segmented in pieces proportional to the bandwidth of the channels available, as separate blocks of data, one for each channel; (3) a request is made to the PCTA for each channel to transmit a block of data; (4) the transmitted segmented data is regrouped back to the original block after the data is transferred over the network; and (5) notice is given to the sending user that the transfer is complete.

The HSDT software package initiates sending each segment over physical channels such that the transfer of data occurs simultaneously at the channels' respective data rates. When all segments of the logical connection have been received at the remote process side, the following preferably occurs: (1) the subscriber is given an indication that a block of data has arrived along with the total length of said data; (2) the subscriber provides a reference to the software product of a reference to memory and the length of this memory; and the software package (3) moves the segments into the subscriber's memory reference such that the resulting block of data matches verbatim the block of data that was initiated from the sending subscriber.

If the need arises to utilize one or more additional physical channels or eliminate one or more of the physical channels that are associated with an existing logical connection, the software package releases/connects these channels. The package preferably: (1) provides which physical channels must be released/connected; (2) waits for latest send request to be completed; (3) waits for latest receive step to be completed if any one or more segments has been received; (4) disconnects/reconnects said channels; (5) adjusts pending send requests segmentation to match new number of available channels; and (6) restarts receives using new segmentation to match the new number of available channels.

The advantages accruing to the method and the subscriber station are numerous. For example, the method and station provide the ability to transfer large amounts of data from one end-user to another using preferably, such standard hardware products as an IBM or IBM compatible personal computer, an ISDN personal computer terminal adapter, an ISDN central office switch (i.e. NTI or AT&T 5ESS switch), and the ISDN.

By connecting two end-users using a number of combined ISDN `B` channels, files can be transferred between the two utilizing the total bandwidth, less any protocol overhead, of these channels. At the same time, two-way messaging is available.

Voice features allow a person to initiate a call from a dialing directory. This directory can also be used to determine the source of incoming calls based on the number of the caller. Provided the PC Terminal Adapter supports a connection to a standard phone, ISDN-type phone features will be made available from the PC (hold, conference, transfer & drop). Voice features can be used simultaneously with data transferring and messaging as long as there is at least one `B` channel available.

The above objects and other objects, features, and advantages of the present invention will be readily appreciated by one of ordinary skill in the art from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a high speed data transfer (HSDT) system of the prior art;

FIG. 2 is a detailed illustration of a subscriber station of the HSDT system hardware of the present invention;

FIG. 3 is an illustration of the layers of the HSDT system software of the present invention and its interaction with the HSDT system hardware;

FIG. 4 is an illustration of the HSDT system of the present invention;

FIG. 5 is an illustration of the main window of the user-interface of the present invention;

FIG. 6a is an illustration of the Setup Call Window;

FIG. 6b is an illustration of the Dialing Directory Window;

FIG. 7 is an illustration of the Disconnect Call Window;

FIG. 8 is an illustration of the Incoming Call Window;

FIG. 9 is an illustration of the Select File to Send Window;

FIG. 10 is an illustration of the Send File Window;

FIG. 11 is an illustration of the Receive File Window;

FIG. 12 is an illustration of the Chat Session Window;

FIG. 13 is an illustration of the ISDN Phone Window;

FIG. 14 is an illustration of the various software modules of the HSDT software and the information flow between during execution of the HSDT software;

FIG. 15 is an illustration of the information flow between software modules during asynchronous events processing;

FIG. 16 is an illustration of the information flow between software modules during disk accesses for configuration and database information;

FIG. 17 is an illustration of the access to the Service Layer and the Resource Management Layer by the Application Layer;

FIG. 18 is an illustration of the information flow between the user and the Application Layer software modules during execution of the HSDT software; and

FIG. 19 is an illustration of the information flow between software modules during user-generated events processing.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring now to FIGS. 2 and 3, an ISDN subscriber station 10 and the HSDT software package (as layers) are shown. In the preferred embodiment, the subscriber station 10 includes an IBM or an IBM compatible EISA- or ISA-bus personal computer 12 having an internal bus 14, a VGA color monitor 16 and VGA adapter card 18, a 101 key keyboard 20, a mouse 22 and an ISDN central office switch, such as the AT&T 5ESS switch (not specifically illustrated). The computer 12 preferably also has at least one ISDN personal computer terminal adapter, such as the Teleos B101PC Terminal Adapter (PCTA) 24, each connected to a Basic Rate Interface (BRI) ISDN line 26 and plugged into the internal bus 14. One of the PCTA's 24 has a standard telephone 28 attached thereto.

The PCTA 24 is an expansion card for an IBM or IBM compatible EISA- or ISA-bus computer. Each BRI line 26 consists of two `B` channels and a `D` channel. A `B` channel is an ISDN path over which voice or data is transmitted. Data can be transmitted at up to 64 Kbps. A `D` channel is an ISDN path through which the associated `B` channels are controlled.

At the other end of the ISDN network, preferably, is a second subscriber station 12' (not specifically illustrated) having substantially the same hardware and utilizing the same HSDT software package. Subscriber station 12' may have a different number of PCTAs 24 than does subscriber station 12. Station 12 and station 12' can perform substantially the same function. A block diagram of the system, showing both ends of the network, is shown in FIG. 4.

It should be noted that in order to have communication between the subscriber stations 12 and 12' running the HSDT software, there must be enough ISDN BRI lines 26 available to support each PCTA 24 in each computer 12.

Additionally, since the HSDT software performs the transfer of large amounts of information, the computer 12 is preferably equipped with a hard disk 30 (not specifically shown). This disk 30 must be large enough to store all files being sent or received, as well as all software necessary for the program to run (DOS, Microsoft Windows, Teleos run-time). The data transfer rate of the disk must be sufficient to support the maximum possible ISDN bandwidth that may be utilized for data transfer.

Since the computer 12 must be capable of transferring data over the bus 14 quickly enough so as to not impact overall performance, the computer 12 is preferably based on a microprocessor having a bus speed of at least 8 MHz, such as the Intel 80286, 80386 or 80486.

The HSDT software was developed using Microsoft `C` version 6.0, Microsoft Windows version 3.0, Microsoft Windows 3.0 Software Development Kit and the Teleos ASK 100 development kit, all commercially available. In the preferred embodiment, the subscriber station 12 will run under IBM PC-DOS version 3.3 (or any MS/PC-DOS version 3.0 or greater) and Microsoft Windows version 3∅ The execution environment will require the Teleos runtime API routines supplied with each Teleos B101PC card.

Although the HSDT software utilizes the Microsoft Windows environment, future applications that utilize the invention are not restricted as to what environment they may run under. This will make access to the capabilities of the software simple and easy to use, and be more appealing to potential customers.

Referring now to FIG. 3, the HSDT software and its interaction with the subscriber station 12 are illustrated by layer. The layered approach was utilized to allow for maximum reusability. The following layers comprise the HSDT software:

Layer 40--Subscriber Station 10 Hardware

Layer 50--Vendor Applications Program Interface (API)

Layer 60--Vendor specific code

Layer 70--Resource Management Layer

Layer 80--Service Layer

Layer 90--HSDT Databases

Layer 100--User interface

It should be appreciated that use of a layered approach permits another vendor's ISDN cards to be used in the final product. This is achieved by isolating the vendor-specific calls to the vendor-specific code layer 60, which makes each ISDN source available.

Other benefits of a layered approach include the availability of various "services" (such as voice capabilities, file transfer, and messaging) that are independent of the hardware configuration of the computer 12. Thus, there is an isolation between the service layer 80 and the resource management layer 70. Furthermore, the service layer 80 implements each ISDN service without any reference to a user interface, allowing for the addition of other services that are not defined at this time. In FIG. 4, the boxes in dashed lines represent such future services/features. Additionally, applications that make use of these services may run under a number of user interface environments.

The layered approach also isolates the developer of a new application from ISDN internals as much as possible, since the developer should only be required to have a general knowledge of ISDN.

In the preferred embodiment, the HSDT software is comprised of a single executable program and a number of supporting data files. It is developed to run on an Intel microprocessor-based personal computer and is designed to transfer data at much higher speeds than is typically possible by making use of the capabilities of ISDN. This high speed transfer is accomplished by linking and synchronizing multiple `B` channels of BRI lines 26 to achieve a higher bandwidth, as described in greater detail herein below.

The User Interface

The user interface runs under the Microsoft Windows version 3.0, presenting a single, consistent user interface to multiple products. It will operate similar to other communications software currently available, thus making the software easier to use. The interface is designed to assure uniformity in appearance and consistency in operation with other existing applications that make use of this environment.

As a part of the user-friendly windowed interface, at various times throughout the course of a session with the software, the user will enter information, and other information will be displayed to the user. This is accomplished through the use of windows. Generally, there are individual windows for each situation confronting the user.

Events can be initiated by either the user or the network. If allowed, the appropriate window for the activity is displayed, and that event is initiated or responded to in this window.

Referring now to FIG. 5, a sample window 110 is illustrated. The Control-menu box 112 is located in the upper-left corner of each window. The Control-menu (also called the System menu) is most useful if you prefer to use the keyboard 20. With Control-menu commands, you can resize, move, maximize, minimize, and close windows, and switch to Task List. (If you are using the mouse 22, you can move, resize, minimize, maximize, and close windows simply by clicking and dragging).

The Title bar 114 shows the name of the particular application. If more than one window is open, the title bar for the active window (the one in which you are working) is a different color or intensity than other title bars. The title bar contains the window title 116.

The menu bar 118 lists the available menus. Most applications have a File menu, an Edit menu, and a Help menu. The HSDT software has these menus as well as additional ones, as described in greater detail herein below.

Horizontal scroll bar 120 and vertical scroll bar 122 let the user move portions of the window 110 into view that are not currently shown. They are used when there is too much information in a window to all be seen at once. They also let the user view unseen portions of lists and other information that is too long to fit in the allotted space.

The Maximize button 124 and the Minimize button 126 (chosen with the mouse 22) enlarge the HSDT window to fill the entire screen or shrink the window to an icon. After the user enlarges the window 110, the Maximize button 124 changes to a Restore button not specifically illustrated. The Restore button is used to return the window to its previous size.

The window border 128 represents the outside edge of the window 110. The user can lengthen or shorten each side of a border if the window has the ability to change size. The window corner 130 can be used to shorten or lengthen two sides of a border at the same time.

The workspace 132 is where most of the work is done. This is where other windows and information are displayed. An arrow-shaped mouse-pointer (not specifically shown) appears if the user has the mouse 22 installed.

The HSDT icon (not specifically illustrated) will appear after the user starts the program and chooses the Minimize command. HSDT will shrink from window size to its icon and continue to run minimized at the bottom edge of the screen. This and other application icons are the only icons that appear on the screen outside the window borders.

Generally, these icons can be moved anywhere on the screen, but not into an open window. Even though Windows will let the user physically place an application icon in an open window, the icon is actually still occupying space on the screen. If the user moves the window, the application icon does not move with it, and if the user closes the window, the application icon remains on the screen.

Another type of icon is called a Document icon. These icons (not specifically shown) appear at the bottom of the application window and can be moved anywhere within the workspace 132, but not outside its borders.

In the preferred embodiment, there are three types of document icons: Call Window icons, File Transfer Windows icons and Chat Window icons. Call Window icons represent a connection, which may be a new call, an incoming call or an established call. The File Transfer Window icons represent any file transfer in progress for a connection, either sending or receiving a file. The Chat Window icons represent a chat session on a connection.

Working with Menus

All user-accessible commands in the HSDT software are listed in menus. The Control Menu opens from the control-menu box 112 in the upper-left corner of each window. Other menus are listed by names in the Menu bar 118 at the top of the HSDT window 110.

To Select a Menu

Point to the name of the menu bar and click the name to open the menu. (Drag the selection cursor down the menu to move to a menu item immediately), or

Press ALT (or F10) to select the menu bar 118. Then press the LEFT ARROW or RIGHT ARROW to select the desired menu. (Using the DIRECTION keys also select the control menu box for the application and the advice document window). Then press ENTER to open the selected menu.

Hint: If the menu names have underlined letters, move to the menu bar, select a menu, and open it with one step. Press ALT, and then press the underlines letter. If more than one menu name has the same underlined letter, Windows selects the first name listed. Press ALT, then the letter again to select the next menu.

To Cancel a Menu

Click the menu name, or anywhere outside the menu, with the mouse 22, or

Press ALT (or F10) to cancel the menu and move back to the workspace 132, or

Press ESC to cancel the menu but remain on the menu bar 118 so that you can select another menu.

Once a menu is selected, an item from it may be chosen by:

Clicking the item name, or

Typing the underlined letter in the item name, or

Using the UP and DOWN ARROW keys to select the desired item; then press ENTER.

All Windows applications follow certain conventions when listing items on a menu. Some menu items may appear dimmed, some may have check marks (.sqroot.) next to them, some may have ellipses (. . . ) after their names, and some may have key combinations listed across from them. These conventions signal that extra information about the menu commands as follows.

______________________________________
Menu Convention
What it means
______________________________________
Dimmed command name
The command is not available at
this time. You might have to
select something before you can
use the command, or it might be
that the command cannot be used
with your application.
An ellipsis (. . .)
A dialog box will appear when
after the name the command is chosen, asking for
information the application needs
to carry out the command.
A checkmark ( )
The command is active. This
next to the name
convention is used for commands
that toggle between one state
and another.
A key combination
The key combination shown is a
after the name shortcut for this command. Use
this key combination to choose
the menu command without first
opening the menu.
A triangle (Δ) at
The command leads to a cascading
the right side of a
menu, which lists additional
menu command   commands that are available.
______________________________________

Within the HSDT software, the main window, an icon, some child windows, and some dialog boxes all have a Control Menu. How the Control Menu is opened depends on whether it is associated with the main window, a child window, a dialog box, or an icon.

To open the Control menu for the main window or an icon:

Click the control-menu box 112 in the upper-left corner of the window or click the icon with the mouse 22, or

Press ALT+ESC repeatedly to cycle through the open application windows and icons, then press ALT+SPACEBAR to open the desired Control menu.

To open the Control menu for child windows or child icons:

Click the control-menu box 112 in the child window or click the child icon with the mouse, or

Press CTRL+F6 (or CTRL+TAB) repeatedly to cycle through open child windows or icons, then press ALT+HYPHEN (-) to open the desired Control menu.

To open the Control menu for a dialog box:

Click the Control menu box in the dialog box, or

Press ALT, SPACEBAR.

The Control Menu pull-down actions include:

Restore returns the window to the size it was and the position it was in prior to a Maximize or Minimize action.

Move allows users to reposition a window on the screen.

Size allows users to change the dimensions of a window.

Minimize removes from the screen all windows associated with HSDT and places HSDT's icon on the screen. Usually this icon is displayed in the lower part of the screen. Users can move minimized icons.

Maximize enlarges the window to the largest possible size, the size of the screen.

Close removes the window and all associated windows from the screen. Close is equivalent to Exit in windows and to Cancel in dialog and message boxes.

Switch to . . . causes the appearance of a dialog box that contains a list of the active applications.

Working With Dialog Boxes

Microsoft Windows uses dialog boxes to prompt information from the user and provide information to the user. Whenever there are ellipses (. . . ) after a menu command, a dialog box for that command follows. Windows also uses dialog boxes to display additional information and warnings, or to explain why a requested action could not be accomplished.

Most dialog boxes contain options, each one asking for a different kind of information. After all the requested information is supplied, a command button is chosen to carry out the command. Dialog boxes that have title bars can be moved around on the screen like windows, as described herein below in greater detail.

Often the need arises to move around within a dialog box to make several selections. The current option is marked by a highlight or dotted rectangle (or both) around the name of the option or button.

To move within a dialog box:

Click the option or group you want to move to with the mouse 22, or

Press TAB to move forward (generally from left to right and top to bottom) or SHIFT+TAB (to move in the opposite direction), or

While holding down the ALT key, type the underlined letter in the option name or group, or

Within a group of options, use the DIRECTION keys to move from one option to another.

Command buttons initiate an immediate action. One command button in each dialog box carries out the command the user selects, using information supplied in the dialog box. Other command buttons let you cancel the command or choose from additional options.

Command buttons marked with an ellipsis (. . . ) open another dialog box for entry of more information. Command buttons marked with a pair of greater-than symbols (>>) expand the current dialog box.

Buttons that are unavailable are dimmed. The currently selected, or default, button has a darker border than the other buttons. The selected button can be chosen by pressing ENTER. The dialog box can be closed prior to completion of a command by choosing Cancel.

To choose a command button:

Click the command button with the mouse 22, or

Press TAB to move to the desired command button. A dotted rectangle around the button text marks the selected button. Then press the SPACEBAR (or ENTER) to choose the button and complete the command.

Hint: If the button has an underlined letter in its name, the command can be chosen in one step. Hold down ALT and press the underlined letter.

A text box is a rectangular dialog box into which information is typed. When moving to an empty text box, an insertion point (flashing vertical bar) appears at the far left side of the box. The text typed starts at the insertion point.

If the box already contains text, all the text in the box is automatically selected and any text typed replaces it. Or, the existing text can be erased by pressing DELETE or BACKSPACE.

To select text in a text box:

Drag the pointer across the text to be selected. Or, double-click to select one word at a time, or

Use the DIRECTION keys to move to the first character to select in the box. Then hold down SHIFT and press a DIRECTION key to extend the selection. (Press SHIFT+HOME to extend the selection to the first character in the box. Press SHIFT+END to extend the selection to the last character in the box).

A list box is a dialog box which shows a column of available choices. If there are more choices than can fit in the list box, scroll bars are provided so that the mouse 22 can be moved up and down quickly through the list.

To select an item from a list box:

Click the scroll arrows until the choice appears in the list box. Then click the item to select and then choose the command button. Or, double-click the item to choose it and complete the command, or

Use the DIRECTION keys to scroll to the item. Or, type the first letter of the item. Microsoft Windows move the highlight to the first item that starts with that letter. Press ENTER to choose the item and complete the selected command.

Option buttons appear in dialog boxes as a list of mutually exclusive items. Only one option can be selected from the list at a time. A selection can be changed by selecting a different button. The selected option button contains a black dot. Unavailable options are dimmed.

To select an option button:

Click the option button with the mouse 22, or

Press TAB to move to the desired option group. Then use the DIRECTION keys to select the option button.

Hint: If the option name contains an underlined letter, hold down ALT and press the underlined letter from anywhere in the dialog box to select an option button.

Check boxes are dialog boxes that offer a list of options that can be switched on and off. Any number of check box options can be selected. When an option in a check box is selected, it contains an X. Otherwise, the box is empty. Names of options that are temporarily unavailable are dimmed.

To select or clear check box options:

Click each empty check box to make a selection, or click a selected box to clear the selection, or

Press TAB to move to the desired empty check box. Press the SPACEBAR to enter an X. Press the SPACEBAR again to clear the selection.

Hint: If the check-box name has an underlined letter, hold down ALT and press the underlined letter for each check box to select or clear.

When a command button has been chosen, the dialog box closes and the command takes effect. To close a dialog box without completing the command:

Choose Cancel, or

Double-click on the System menu box, or

Press ESC.

For dialog boxes that do not have Cancel buttons, choose the Close command (press ALT+F4) from the System menu. For dialog boxes that do not have Cancel buttons or System menus, choose the appropriate button.

Working with a Window

When working with the HSDT software, a number of different windows will usually be open. Some methods of organization are listed herein below. The Microsoft Windows User's Guide provides additional detail.

Move application windows, document windows, and icons to different places on the screen. Move any dialog box that has a title bar.

Change the size and shape of most windows on the screen. If using a mouse 22, drag each side of the window border or its corners to adjust its size. If using the keyboard 20, the commands on the System menu allow the window's size and shape to be modified.

Shrink a window to an icon when finished working with an application or document window, although still available for later use. When an application window is shrunk to an icon, the application is still running in memory, but its window is not taking up space on the screen.

Select and move icons on the screen in the same way windows are selected and moved. Double-click the icon to restore the window (or use the Maximize or Restore commands on the System menu).

Enlarge the windows to fill a larger portion of the desktop or even the entire desktop.

Restore an icon or a window. The Restore command returns a window or an icon to the size and position it occupied before it was enlarged or shrank to an icon.

Some windows and dialog boxes have scroll bars to view text that requires more than the available space.

When working with an application window, one way to exit from the application is to close the window. Similarly, when working with a document window, exit from that document by closing the window.

Working with HSDT

In the preferred embodiment, there are two methods of starting the HSDT from the Program Manager. The first is to choose the HSDT item from a group window. Alternatively, the user can select the Run command from the File menu. The user, however, must type the complete pathname to HSDT including its name and extension.

In order to make the HSDT software user-friendly, the user interface was designed:

1) To present the user with an interface that is consistent across all applications that run under the Microsoft Windows environment. This aids users in learning new applications more quickly and easily.

2) To make the interface simple to use. The user should not have to bother with the mechanics of the interface that make the application work. They should instead be able to concentrate on accomplishing their tasks.

3) To make the interface natural. The operation of the program should be intuitive so the user can anticipate what to do at each step.

4) To allow the user to control the dialog. When the user is in control, they can switch from one activity to another, change their ends easily, and stop activities they no longer want to continue. Users should be able to cancel or suspend any time-consuming activity without causing disastrous results.

5) To make the interface forgiving. User actions should be easily reversed. They should be able to explore without fear of causing an irreversible mistake. Destructive actions (that may cause the unexpected loss of the user's information) should require a confirmation.

6) To provide immediate feedback. Users should never press a key or select an action without receiving immediate visual feedback, audible feedback, or both.

Most of the features of the HSDT software are accessed from menus. These menus are located at the top of the main window on the menu bar 118. They can be accessed with either the mouse 22 or from the keyboard 20. Each menu, its description, and the functions it contains follows (each menu is not specifically illustrated for the sake of clarity):

The Services Menu provides the user with service oriented functions. The Services Menu pull-down actions include:

Setup Call allows the user to establish a new connection.

Send File allows the user to send a file over an established connection.

Send Message allows the user to send a message over an established connection.

Chat Session allows the user to chat over a connection.

ISDN Phone allows the user to place a voice call.

Exit allows the user to exit the HSDT application.

The Options Menu provides a means for users to customize the HSDT software. The Options Menu pull-down actions include:

Auto Answer allows other applications to connect to this one without requiring any user action.

Auto Receive allows other applications to send files to this one without requiring any user action.

Return Receipt enables the user to receive a confirmation that a message sent to another workstation was received.

Refuse Messages provides the user with the choice of refusing to receive any messages sent from other workstations. If this option is selected and another user tries to send a message, the other user will receive a message that messages are not being accepted.

Refuse Chat provides the user the choice of refusing any chat sessions requested from another workstation. If this option is selected and the other user attempts to "chat", the other user will receive a message that chat sessions are not being accepted.

The Window Menu provides a means for users to customize the HSDT application. The Window Menu pull-down actions are:

Cascade will move and resize all open HSDT windows such that the title bars of all of them are visible.

Title will move and resize all open HSDT windows such that none of them overlap.

Arrange Icons will move all minimized HSDT document icons and align them along the bottom of the HSDT communications window.

Below these menu items will be a listing of all HSDT document windows, whether they are open or iconized (i.e. minimized). The currently active window will have a check mark next to it. From this menu, the user can move to any HSDT window.

The Help Menu allows users to access the on-line help system built into Windows, as well as getting information about HSDT. The Help Menu pull-down actions include:

Help on Help allows the user to get help on using the Help system.

Index accesses the on-line help system and gives the user an index of all available topics relating to HSDT.

About HSDT gives brief information about the HSDT application.

The Control Menu is available in the title bar 114 of all windows in HSDT to provide keyboard access to all actions that users can perform on a window, such as moving and sizing.

Accessing and Using Help

Help with the HSDT software is provided by using the Help facility that is provided with Microsoft Windows. It is in reality a separate program, but to the user, it appears to be part of the software they are running.

It should be noted that the purpose of Help is to provide the user with additional information about HSDT. It is not meant to tutor users. Tutorials teach new users how to use an application; help information should help users recall how to use an application. A tutorial is not provided with HSDT, only a Help reference. If the user is unfamiliar with the Help system, Help on Help may be chosen for assistance.

Task Specification

The following describes in detail each task that can be accomplished by the HSDT software when transferring data.

Establishing a Logical Connection

This command will only be available if there is at least one available `B` channel. Before any data can be sent or received by the first subscriber station 12 utilizing HSDT, a logical connection must be established with another subscriber station 12'. This connection is made by choosing the Setup Call command from the Services menu.

When this command is chosen, the user is presented with a Setup Call Window 140, a new connection window containing connection information, as illustrated in FIG. 6a. At the top of the window 140 is a Call Information Box 142, which contains the number to be called and the name associated with the number to be called. These are to be supplied by the user either by typing the number in the number field or by choosing an entry from the Dialing Directory, as described in greater detail below.

Below this box is a Channel Information Box 144, which contains usage information to be set by the user. The user can select to use either all available B channels by selecting the All Available button or only some of the available channels by selecting the Only Use button and entering the exact number of channels to use in the adjacent field.

Below the Channel Information Box 144 is the Rate Adaptation Box 145, where the user can specify the rate at which the data transfer will occur. Preferably, the user can select from 64 Kbps clear, 64 Kbps restricted or 56 Kbps clear. As is known, some transmission lines utilize one or more bits, depending on the amount of data transferred, to effect proper transmission. For example, the line may use one bit for every 3 bytes transferred. Such a transmission line is generally termed "restricted", while one that does not utilized any bits is generally termed "clear".

Below the Channel Information Box 144 is the Status Box 146 where status messages relating to the connection are displayed to the user. To the right of the boxes 142 through 146 are a plurality of buttons, the names of which appear in normal text or italicized text. The buttons appearing with normal text can be selected by the user. Thus, when the Setup Call Window 140 is displayed to the user, only the Connect button 148, the Dialing Dir. button 150 or the Cancel button 152 may be selected by the user.

Selecting the Connect button 148 results in the software attempting to place a call. If the connection is established, the title of the window will change from "Call New" to include the number connected thereto.

After selecting the connect button 148, the HSDT software package preferably performs the following steps to establish the single logical connection: (1) matches each given rate adaptation with an available `B` channel; (2) sends the rate adaptation list to the subscriber station 12' (remote process) using the given phone number (or ISDN address), and phone number to dial back; (3) the subscriber station 12' delivers this list to the user of the software; (4) the user may modify the rate adaptations and/or eliminate some, and presents this list back to the HSDT software package; (5) matches this new list to available compatible channels; (6) sends back the modified list along with phone numbers for each `B` channel; (7) each `B` channel is dialed up in order to make the physical connection using the new

rate adaptation list; and (8) once all the `B` channels in the list are established as physical connections an exchange of information is made to synchronize the channels and the subscriber station 12 is given a `handle` on this one logic connection.

Selecting the Dialing Dir. button 150 will result in the dialing directory being accessed, as described in greater detail below. The user may exit this window by selecting either the Cancel button 152 or Close from the window's Control menu. Additionally, the Setup Call Window 140 may be minimized at any time.

Selecting a Dialing Directory Entry

This command is available from the Setup Call Window 140. As noted above, when a user wishes to choose a number from the directory, the Dialing Dir. button 150 must be selected.

As best shown in FIG. 6b, the user is presented with the Dialing Directory Dialog Box 154 to select an entry when the Dialing Dir. button 150 is selected. The entries field 156 contains all available entries. The entries field 156 is scrollable, such that a scroll bar (not specifically illustrated) will appear on the right edge of the box to allow the user to view more entries.

The user moves the selection bar with the up/down arrow keys or mouse, thereby highlighting an entry. Additionally, the user may simply type a letter and the selection bar will automatically move to the next name beginning with that letter.

Choosing the Select button 158 will close the box 154 and the user will be returned to the Setup Call Window 140. The name and number selected will appear in the Call Information Box 142. Selecting the Cancel button 160 will similarly close the box 154 and the user will be returned to the Setup Call Window 140, but the name and number fields in the Call Information Box 142 will not be altered.

Terminating A Connection

This command will only be available if at least one logical connection exists. When a user no longer desires to be connected to another system, a connection can be terminated utilizing the Disconnect Call Window 161 shown in FIG. 7. It should be noted that the Disconnect Call window 161 is substantially the same as the Setup Call Window 140, except that disconnect button 149 is the only button that appears as normal text (i.e. can be selected) to the user.

When a data connection is established, the title of the Call window reflects the number connected to (or the name if the number is listed in the Dialing Directory), and information about the connection is displayed in the Call Information Box 142, the Channel Information Box 144 and the Status Box 146.

If the window 161 is displayed, the user may select the Disconnect button 149 or select Close from the window's Control Menu. If the window is an icon, the user can still disconnect by highlighting the icon and selecting Close from the Control Menu.

Choosing the Disconnect button 149 or selecting Close from the Control Menu will result in the connection being terminated and the Call window disappearing. Also, the window will be removed from the list under the Window menu. If for some reason the connection could not be terminated, a message box will appear informing the user.

Instead of a complete disconnection, the need may arise to add or eliminate one or more of the physical `B` channels that are associated with an existing logical connection. It should be appreciated that the HSDT software package could preferably release/connect these channels by (1) providing to the user which physical channels must be released/connected; (2) waiting for the latest send request to be completed; (3) waiting for the latest receive step to be completed if any one or more segments has been received; (4) disconnecting/reconnecting and relinking said channels; (5) adjusting pending send requests data segmentation to match the new number of available channels; and (6) restarting receives using the new segmentation to match the new number of available channels.

Handling An Incoming Connection Request

The first subscriber station 12 may connect to a request from a second subscriber station 12' only if there is at least one available `B` channel to support the request. Thus, if all `B` channels of subscriber station 12 are utilized and the subscriber station 12' requests a connection to the station 12, a `B` channel must be made available before the subscriber station 12 can connect to the request.

Before any data can be sent or received by HSDT, a logical connection must be established as described above with the subscriber station 12'. This connection may be initiated by another user. When a request for a connection comes in from the network, the Incoming Call Window 162, as shown in FIG. 8, will appear. While the window can be minimized, the user should respond to any request as quickly as possible.

It should be appreciated that this command cannot be accessed from the menu. It should be noted that the Incoming Call window 162 is substantially the same as the Setup Call Window 140 and the Disconnect Call Window 161. When the Incoming Call Window 162 is displayed, however, only the Accept button 164 and the Reject button 166 appear as normal text to the user.

The Incoming Call Window 162 contains information about the request and fields to modify the connection parameters. As noted above, the Call Information Box 142 contains the number of the caller and the name associated therewith, if one can be found. The Channels Information Box 144 contains channel usage information, which is modifiable by the user before accepting the call. The Status Box 146 contains messages relating to the connection.

The number of `B` channels to use can be set from the Channels Information Box 144. The user can select to use either the number of `B` channels requested by the sending subscriber station 12' by making no modifications, or the user can select only some of the available channels by selecting "Only Use" and entering an appropriate number. Thus, the user may establish a connection at a lower bandwidth than that requested. In the preferred embodiment, a higher bandwidth than that requested can not be established, although establishing a higher bandwidth than that requested is possible.

By selecting the Accept button 164, the program accepts the call with the parameters selected. If the connection is established, the title of the window will change to include the number (or name if the number is listed in the Dialing Directory) connected thereto. If the Reject button 166 is selected, a reject message will be sent to the subscriber station 12' and the window 162 will be closed.

Selecting a File to Send

This command will only be available if at least one logical connection exists. When a user wishes to send a file (e.g. to the subscriber station 12'), a file to send must be selected. This is done by choosing the Send File command from the File menu. When this command is chosen, the user is presented with the Select File to Send Window 174, as shown in FIG. 9. The Select File Window 174 allows the user to select a file to transfer. At the top of the box 174 there will be several fields containing information on the currently selected file. These include the file name field 176, path field 178, and the size field 180. Below these fields are two list boxes. The Files box 182 contains a list of all files in the current directory for the user to choose from. The Directories box 184 contains a list of all subdirectories of the current directory, the parent directory of the current directory, and a list of all other available drives. Above and to the right of the Directories list box 184 are the Select button 186 and the Cancel button 188.

Preferably, the user selects a file to send by selecting a file from the Files list box 182, a static display field. Of course, the file name field 176, an edit field, could be utilized, wherein the user would type in a file name. The user can change directories or drives by choosing entries from the Directories list box 184.

Choosing the Select button 186 with a file selected or double-clicking on the filename to send will close the window and the software package will allow the data to be sent over the logical connection by: (1) reading the file from the hard disk; (2) providing a reference in memory to the contiguous block of data to be sent; and (3) the length of data to send. It should be noted that the file is read from the disk in "pieces" or "blocks", and that steps (2) and (3) are performed for each "block." The Send File Window discussed in greater detail below, will be displayed during the transfer.

In preparing to send data, the HSDT software package breaks the data up into segments of varying length, one for each `B` channel in use. The length is proportional to each channel's data rate.

In the preferred embodiment, a request is first made to send a block of data (e.g. send "ABCDEFGHIJKLMNOPQRSTUVWX"). Next, the block is "segmented", or copied in pieces proportional to the bandwidth of the `B` channels available, as separate blocks of data, one for each channel (e.g. the block may be segmented as "ABCDEFGHIJKLMNOPQR", "STU" and "VWX" for transfer over an "HO" and two (2) `B` channels, respectively). A request is then made to the PCTA 24 for each `B` channel to transmit a block of data over the network. After the data is transferred over the network, the segmented data is regrouped back to the original block (e.g."ABCDEFGHIJKLMNOPQRSTUVWX"). A message that the file transfer is complete is then provided to the sending user. It should be appreciated that buffering with a cache memory or the like could be employed to facilitate the data segmentation and transfer.

Since each user can not guarantee which of their available `B` channels will be utilized for the transfer, the HSDT software performs an information exchange between the subscriber stations 12 and 12' to synchronize the channels. The synchronization, which occurs at the time the logical connection is made, operates to match `B` channels on opposite sides of the network (e.g. the first `B` channel of station 12 is matched to the first `B` channel of station 12'. The user of subscriber station 12 sends a string whose length depends on the number of channels being used (i.e. a 6-byte string for 6 channels) through the segmenting process. Preferably, the first byte has a value of 1 and is sent over the first `B` channel, the second byte a value of 2 and is sent over the second `B` channel etc., such that the string is transmitted as 1-2-3-4-5-6. If the channels are not synchronized, the subscriber station 12' may receive this string as 3-4-1-5-2-6, indicating the first channel of station 12 is communicating with the third channel of station 12', etc.

The HSDT software then logically orders the channels of station 12' such that the first channel on station 12' is in communication with the first channel of station 12, the second channel of station 12' is in communication with the second channel of station 12, etc. and sends the same string over the network back to station 12 for verification of synchronization.

The HSDT software package initiates sending each segment over the `B` channels such that the transfer of data occurs substantially simultaneously at the channels' respective data rates. When all segments of the logical connection have been received at the subscriber station 12', the following occurs: (1) the user of subscriber station 12' is given an indication that a block of data has arrived along with the total length of said data; (2) the user provides a reference to the HSDT software product of a reference to memory and the length of this memory; and the HSDT software package (3) moves the transferred segments into the memory (e.g. a buffer) of subscriber station 12' at the reference such that the resulting block of data matches verbatim the block of data that was transferred from the sending subscriber station 12.

It should be appreciated that a protocol process could be utilized in the PCTA 24 to implement the actual transfer over independent `B` channels. With the protocol process, the information to be sent is "packaged" with additional information, such as error check bits. When the information is received, the receiving station utilizes the error check bits to verify the integrity of the information sent.

Choosing the Cancel button 188 will close the window and return to the main window. The user may exit this window by choosing either the Select button 186 or the Cancel button 188.

Sending A File Progress

This operation will only transpire if the user has selected a file to send from the Select File to Send Dialog Box 174 or if an incoming file request has been accepted. When the user selects a file to send, the Send A File Window 190, as shown in FIG. 10, will be displayed. It should be appreciated that this window cannot be directly accessed from the menu.

The Send A File window 190 primarily relays information and requires little or no user input. At the top of the window is the File Information Box 192, which contains information about the file being sent or received. This preferably includes the name and path of the file on the local machine. The Transfer Information Box 193 also contains information relating to the transfer, preferably the estimated total time of the transfer, the elapsed time of the transfer thus far, the approximate kbps rate of the transfer, the total number of bytes to send and the number of bytes sent thus far. This information is updated as the transfer progresses. The Status Box 194 operates to provide the user with messages, such as how to initiate the file send or to indicate the file transfer has been completed.

The only controls the user can control are the Start button 195 and the Abort button 196, both located generally at the bottom of the screen. The Start button 195 is utilized to start the file send and the Abort button 196 should be selected to stop the transfer before it has completed.

This window may be minimized by the user if they do not wish to watch the file transfer. This may be useful, for example, if a long file transfer is started and the user wishes to `chat` with the subscriber station 12' during the transfer.

The user can thus exit the window by selecting the Abort button 196. Additionally, the window will close after the user responds to the message that the transfer has completed successfully.

Receiving a File

The ability of a first subscriber station 12 to receive a data transfer allows a second subscriber station 12' to send data at any time, simultaneous on all `B` channels at their respective data rates. The ability to receive a file, however, will only be available if at least one logical connection exists. When a request for a file transfer comes in from the network, the Receive File Window 200, as shown in FIG. 11, will appear. It should be appreciated that this command cannot be accessed from the menu and that the user may set up the station 12 to automatically receive file by selecting the "Auto Receive" option from the Options Menu.

The Receive File window 200 is similar to the Send A File window 190. At the top of the window is the File Information Box 202, which contains information about the file being sent or received. This preferably includes the file name and path specified by the sending subscriber station 12'. The Transfer Information Box 204 also contains information relating to the transfer, preferably the estimated total time of the transfer, the elapsed time of the transfer thus far, the approximate kbps rate of the transfer, the total number of bytes to receive and the number of bytes received thus far. This information is updated as the transfer progresses. The Status Box 206 operates to provide the user with messages, such as how to initiate the receipt of the file or to indicate the file is being received automatically, if the Auto Receive option is set.

The only controls the user can control are the Start button 208 and the Abort button 210, both located generally at the bottom of the screen. The Start button 208 is utilized to start the file receive and the Abort button 210 should be selected to stop the transfer before it has completed. If the file transfer completes successfully, a status message will appear indicating the transfer is complete and the window 200 will then disappear.

When all segments of the logical connection have been received, the following occurs: (1) the first subscriber station 12 is given an indication that a block of data has arrived along with the total length of said data; (2) the user of subscriber station 12 provides a reference to the HSDT software of a reference to memory and the length of this memory; the HSDT software package (3) moves the transferred segments into the memory of subscriber station 12 at the memory reference such that the resulting block of data matches verbatim the block of data that was transferred from the sending subscriber station 12'. The segments are then written to the disk file.

Choosing the Reject button 210 will close the window and return to the main window. The user may exit this window by choosing either the Accept button 208 or the Reject button 210.

Sending a Message

The ability to send a message will only be available if at least one logical connection exists. When a user wishes to send a message to another system, they will enter "chat mode" and the Chat Session Window 212, as shown in FIG. 12, will be displayed. This is done by choosing the Chat Session command from the Services menu.

The Chat Session Window 212 is preferably split into two sections. The Remote Box 214 of the window is where received messages will be displayed. The Local Box 216 is where messages to send may be typed. The user can send a message by simply typing in the lower window. Hitting the Enter key after each line will cause it to be sent. The window can be minimized in order to see other windows if desired. The window 212 is closed by selecting Close from the window's Control menu.

Instead of an interactive "chat", the user may wish to just send a message to the other user. To send a message, the Send Message command is selected from the Services Menu. The Send Message Window (not specifically illustrated) will appear. The Send Message Window consists of a small box in which the user types the message to be sent. When the user has typed in the message, it can be sent selecting the SEND button. The sender may instead CANCEL the message operation. The send can request a return receipt by checking the return receipt entry in the menu. If the Return Receipt option from the Options Menu is selected, a message informs the user that the message was read.

Receiving a Message

Similarly, the ability to interactively "chat" or to receive a message will only be available if at least one logical connection exists. When a message is received from a remote subscriber station 12' over the network, the receiving station 12 will enter "chat mode" and the Chat Session Window 212 will be displayed, as described above. If the station 12 is already in this mode, the message will simply appear in the Received Messages portion of the window. As noted above, the Remote Box 214 is where received messages will be displayed. The user can response to the messages by simply typing them in the Local Box 216. The user may exit this window by selecting close from the Control menu.

Voice Features

The HSDT software will provide the features of an ISDN phone on the PC, so that even an analog-type phone may be used as an ISDN phone through the combination of the phone, the software and the ISDN PCTA. When voice features are active, the ISDN Phone Window 220, best shown in FIG. 13, appears. Voice features can be activated from the Setup Call Window 140 or by lifting the phone hook and are implemented by the AV module of Layer 50.

In the preferred embodiment, the ISDN Phone Window 220 contains an edit field 222, a keypad 224, a plurality of function buttons 226, a plurality of feature buttons 228 and a display area 230 in which call appearances are displayed. As shown, a call appearance includes the status of the call (i.e. held, incoming), the phone number and the name of the party associated with that phone number. The edit field 222 is a field into which a telephone number may be typed by the user. The display area 230 also includes an Incoming Call Identification (ICI) field 232, in which information relating to the call (e.g. incoming, outgoing, etc) is displayed.

The function buttons 228 provide the user with a variety of phone features common to an ISDN phone, such as hold, drop, transfer and conference. Additionally, "Clear" allows the user to erase the number typed into the edit field 222. However, if the user wishes to use the number entered into the edit field 222, the Dial function button is preferably selected to place the call.

Instead of typing a number into the edit field 222, the user may select the Dialing Dir button and select a number from the dialing directory. To select a call appearance (e.g. pick-up a call placed on "hold"), the user preferably can either "click" the mouse on the feature button 226 adjacent to the desired call appearance, or type in the feature button number in the edit field 222 and then select the Press function button 228.

In the preferred embodiment, the phone window is opened when a call appearance is active, or when an "off-hook" or incoming indication is received while an incoming call is not present (i.e. just as though the phone option had been selected from the Services menu). The phone window is also opened when an incoming call is attempting to make a connection, and the caller is identified to the user. It should be noted that the same window is utilized on both the calling station and the called station of the connection. Any user messages originating from the central office 5ESS switch, the PCTA board or the software will be displayed in the window to the user.

When a completed call is terminated, the phone window preferably remains displayed and the `B` channel reserved for the call remains reserved (i.e. just as though the phone option had been selected from the Services menu). It should be appreciated that the phone window, like the other windows previously described, may be minimized by the user, even while a call is in progress. The phone service will be ended (and the reserved `B` channel released) when the phone window is closed by the user.

The phone option is present on the Services menu. The phone option on the Services menu is preferably "grayed" when the option is not available. When the phone option is selected from the services menu, the software reserves a `B` channel on the first PCTA card for voice and the phone window 220 is opened for the user. As discussed above, the user preferably dials a phone number by using the dialing directory or typing the number into the edit field 222 of the window. The user may also dial the number directly on the phone 28 keypad. If the number is dialed directly on the phone keypad, the number may show up in the window (depending on the type of PCTA utilized) since the software does not sense the phone's numeric keys being depressed.

A Voice call connection is possible if a `B` channel has been reserved or is available. Although existing connections are preferably not "juggled" to accommodate a voice connection, such a feature is possible.

In the preferred embodiment, a software module accommodates the necessary code for handling regular voice phone calls. The module includes a procedure exported to Windows for handling messages from the Windows event queue (i.e. AV_-- WndProc). The phone option setup routine is preferably labeled AV_-- Setup, and its completion routine is labeled AV_-- Cleanup. The setup and cleanup routines have CreateKids and KillKids routines to do the actual creation and destruction of buttons, text, etc. on the phone window, which is the "parent" of these objects. The messages concerning the call itself (e.g. on-hook, off-hook, display messages, feature messages, etc.) are passed into the module by calling AV_-- Event (which processes Resource Layer events).

Voice Call Window

When a voice call request arrives (a call appearance is active), the ISDN Phone window 220 displays information on the call such as the calling party's number, the calling party's name (if it is found in the Dialing Directory). As previously described, for a voice connection to be permitted, at least one `B` channel must be available. In the preferred embodiment, this allows for voice connections even during high speed data transfers (i.e. simultaneously). The window is removed when the phone 28 is placed on-hook or the Reject button 166 is chosen.

User And Network Initiated Events

Events can be initiated by the user or by the network. If allowed, the appropriate window for the event is displayed and that event is initiated or responded to in that window.

Request Data Connection

This event is initiated by the USER upon choosing the Setup Call command, thereby establishing a logical connection with a remote subscriber station 12'. This request may only be made when there is an available `B` channel. The system allows for multiple data connections to be established, up to the number of `B` channels that exist. Additionally, if the voice features are active, the maximum bandwidth available will not include one of the `B` channels (the one being used for the voice connection). First, the user enters the `Setup Call` window 140, selects the bandwidth (i.e. number and type of channels to combine), data rate and number to call and chooses CONNECT. The subscriber station 12' sees the `Incoming Call` window 162 to acknowledge the connection. Once the connection is established, either user may initiate file sends, or send a message. Statistics on this existing connection are displayed in the `Connection statistics` window, when selected.

Incoming Data Connection Request

This event is NETWORK initiated, when a first user requests a connection with a second user. If there are no `B` channels available, an automatic denial or rejection is sent back to the requester. If the connection is allowable, the user still has the option to either ACCEPT or DENY the connection request. Once a connection is established, either user may initiate File Sends, Chat Message, or Send Message.

Phone Off-hook to Initiate Voice Call

This event is USER initiated and is allowed only when there is an available `B` channel on the B101 PCTA 24 connected to the phone 28. When there is not an available `B` channel, an appropriate message will be displayed. Whenever the phone 28 is `off-hook` and a `B` channel is available, the ISDN Phone window 220 will be displayed. The user may initiate a call by dialing on the phone 28 (provided the PCTA supports the capability), using the keyboard 20 to type a number into the window, or making a selection from the dialing directory. While a voice call is active the user may choose hold, conference, transfer or drop from the window. To remove the ISDN Phone window 220 the user must hang up the phone 28. The feature buttons 226 may be selected by typing the desired feature button number in the edit field 222 and then "clicking" on the Press function button 228.

Phone On-hook to End Voice Call

This event is USER initiated by placing the phone 28 back `on-hook`. If the ISDN Phone window 220 was displayed, it will be removed by this event, provided that no other Call Appearances are active. In the case that the phone 28 was initially taken off-hook when a voice call was not allowed, causing an appropriate message window to appear to the user, placing the phone 28 back `on-hook` will remove this message window.

Incoming Voice Call Request

This is a NETWORK initiated event. When this request is received, the `Incoming Voice Call` window will appear. The user can pick up the phone 28 to accept the call, or may press the associated call appearance button to pick up the speaker phone (i.e. if the PCTA is so equipped).

Initiate Disconnect of Data Connection

This USER initiated event occurs when the user wishes to terminate an existing logical connection. The user enters the Disconnect Call Window 161 and select the Disconnect button 149. If a File Transfer or Chat Session is in progress when the Disconnect button 149 is selected, they will be aborted and the window will be closed.

File Transfer Aborted

Initiated by the USER, this event occurs by selecting ABORT from the Send File Window 190. This event removes the `File Transfer In Progress' window 190 from the screen. At this point, the other side of the connection receives the `File Transfer Aborted` event as a NETWORK initiated event. This causes a message to be displayed indicating that the transfer was aborted. When the receiver selects OK, the File Transfer Window 190 will disappear and the file transfer process will have been aborted.

Data Disconnect Received

This is a NETWORK initiated event. When the logical connection is terminated, both subscriber stations 12 and 12' will receive the message `Connection Terminated`. The message remains on-screen until the user selects `OK`.

Initiate File Transfer

Initiated by the USER, this event is executed from the `Select File To Send` window 174. As described above, this window is available only if a logical connection exists. When available, the user selects a file to send and chooses either SELECT or CANCEL. Before the user choose SELECT or CANCEL, statistics on the currently selected field will be displayed, showing file size, estimated time to send, etc. As described above, once SELECT is chosen, the `Select File To Send` window 174 will be replaced by the Send File Window 190, and the status of the transfer will be displayed there. The receiving side will get an indication that a file transfer has been requested, and has the option to ACCEPT or DENY the transfer.

File Transfer Completed

This event, initiated by the NETWORK on both sides, causes a message to be displayed indicating that the high speed data transfer was successfully completed. When the user selects OK, the Send File Window 190 will disappear.

Receive File Transfer Request

This is a NETWORK initiated event which will cause the `Receive File` window 200 to be displayed. Within the window 200, the user will be able to select a file path and a file name to save the file. Various statistics relating to the receive will be shown, including file name, size of file, estimated time to send, and the path. If there is not sufficient space on the disk selected, ACCEPT will not be available. ACCEPT when available or DENY with an optional reason must be selected.

Send a Message

This USER initiated event is only available if a logical connection exists. Once the Send Message window (not specifically illustrated) appears, and the user has typed in the message, it can be sent by choosing SEND or it may be cancelled by choosing CANCEL, as previously described. If SEND is chosen, a `Receive Message` event, described herein below, will occur on the receiving subscriber station. The message can then be removed by choosing OK.

Receive a Message

This event is initiated by the NETWORK when a remote station sends a message. This causes the Send A Message window to appear displaying the message sent. To insure that the message gets read by the user, this window will remain until OK is selected.

Chat Session

This is a USER initiated event at one end of the network (the end from which the chat session is originating), and a NETWORK initiated event at the other end. This event causes the Chat Session Window 212, as described in greater detail above, to appear on the screen.

HSDT Control Flow

Turning now to FIG. 14, the entire data and control flow through the HSDT software during its execution is shown. FIG. 14 also shows every module that comprises the software and shows how information flows between them. Generally, the modules are grouped into their respective layers.

FIGS. 15-19 break the program and control flow into more manageable and understandable parts. In general, the following rules apply to the diagrams:

(1) Arrows pointing "up" are function calls.

(2) Arrows pointing "down" are callback functions.

The two-letter codes associated with each module, such as "VX", are intended to be used to identify the source code filename for this module as well as prefixing each of the public interface symbols (function names, typedefs, #defines, etc.) within the module. Each of these modules are intended to be implemented as a single source code file. For clarity, public symbols should be placed in a header file of the same name (i.e. VX.C and VX.H).

In the preferred embodiment, program execution is divided into 5 general areas of flow. They are:

1. Asynchronous events (FIG. 15);

2. Disk access (FIG. 16);

3. Service Layer 80 and Resource Management Layer 70 support (FIG. 17);

4. User/application communication (FIG. 18); and

5. User generated events (FIG. 19).

Each of these areas are described in detail herein below.

Asynchronous Events

FIG. 15 shows the flow of asynchronous events through the modules involved in processing these events.

Asynchronous events can potentially occur at two locations: Keyboard and Teleos hardware. All user (keyboard) events are synchronized by Microsoft Windows, discussed in greater detail below, and delivered to the main application when requested (i.e. not asynchronously). All network (Teleos) events are delivered to the VX module as asynchronous events. These events are then delivered to the RI module either through interrupts, or polled through VX_-- Poll().

__________________________________________________________________________
FLOW:    EVENTS       PROCESSING AT DESTINATION:
__________________________________________________________________________
VX > RI  Voice state changes
Passed directly to RI
B Channel:   Passed directly to RB as
control and data
X.25 Sessions control:
Dealt with internally to RI
X.25 Session data
Passed to RB
RI > RA  Voice state changes
Passed directly to RA
RI > RB  B Channel control:
Used to indicate connection
up/down
B Channel data sent
Notify sender (SM or SF)
B Channel data rcvd
Deliver as session (SM/SF)
or non-session (AC)
Connection setup
Begin B channel connections
Connection request
Locate application callback, send to AI
RA > SV  Voice state changes
Converted to three possible
events for AV
RB > AC  Connection up
Remove dialing window
Connection lost w/reason
Update connection view
window, show user
Non-session data
Deliver as new service
requests
RB > SF or SM
Session lost Cleanup service, tell AF or AM
Session data received
Prepare to store buffer to
disk & mark buffer free
RB > AI  Connection request
Passed to the AC module
SV > AV  Hook state change
Que to create/destroy voice
window
Call connected
Que for display
Call disconnected
Que for display
w/reason
SF > AF  Service lost Remove file transfer window,
cleanup
AI > AC  Connection request
Allow user negotiation of
connection
AC > AF  File send request
Que to handle later
AC > AM  Message received
Que to display message to
user, notify SM
AM > SM  Message data received
Copy to local buffer
__________________________________________________________________________

Disk Access

FIG. 16 illustrates which modules are involved in accessing data files on the disk 30 for configuration and database information.

Access to the hard disk is required once at startup to get configuration information, much of which is sent to the Resource Management Layer 70 to identify the ISDN hardware configuration, and during runtime to locate and list names and associated phone numbers. The latter accesses are required either when a connection request is received and the associated remote phone number must be identified locally for the user, for connection acceptance, or when a connection request is being made locally, to allow the user to choose from a list of names to connect to.

______________________________________
USER > DISK
Modifications of data files outside scope of this
program
WIN > USER Displayed names/addresses in graphics
window
DISK > WIN Access to WIN.INI file (formate described
below)
DISK > DN  Names and Addresses file access
AC > DN    Calls to get name and address information
AC > WIN   Write to window to display name and address
information
WIN > AI   Delivery of WIN.INI file information
AC > RB    Final phone number choice delivered to
resource layer
AI > RA    Initialization of Res. Mgmt. Layer 70 using
WIN.INI config settings
RA > RI    Initialization of ISDN hardware parameters
passed up to RI module
______________________________________

Database File Structure

The database file is completely accessed though the DN module (part of the Database Layer 90) by the AC module (part of the Application Layer 50) which is managing connections for the HSDT software. In the preferred embodiment, the DN module will utilize a single disk file (NAMES.DAT) that will be built using a user's favorite text editor.

The Names and Numbers database will exist as a flat ASCII file and consist of lines of the format: Name:Number. The Name field can be up to 64 characters long and may contain spaces. The Number field can be up to 24 characters and may contain some other characters. Dashes and Parens can be included and will be stripped for dialing purposes. Ex: John Q. Public:1(303)930-2544 is acceptable.

The configuration information will be located in a single disk file (WIN.INI) that conforms to the Microsoft Windows "INI file" format described below. Access to this file will be made by the AI module through Microsoft Windows API during runtime, and may be modified by the user using NOTEPAD or by invoking the user's favorite text editor.

Under an entry called [HSDT], the following lines may exist: Label=value

Currently, the following labels and value ranges may be specified: Cards=n where `n` may be 1, 2 or 3

The following lines must be specified many times (2 times `n` above). Each line must have a unique `Label` by specifying different values for `C` and `B` Phone C,B=####### `C` between 1 and `n` above; `B` is 1 or 2

An example WIN.INI file for two cards on the AT&T 5ESS switch (`B` channels have same number) is as follows:

Cards=2

Phone 1,1=2901009

Phone 1,2=2901009

Phone 2,1=2901010

Phone 2,2=2901010

Service Layer and Resource Management Layer Support

FIG. 17 shows the access to the Service Layer 80 and the Resource Management Layers 70 by the Application Layer 50.

Each module's access needs toward the service and resource layers are as follows.

______________________________________
AI > RA  Initialize resource layer/register application by
name;
Clean up resource layer
AC > RB  Make a connection request;
Acknowledge a request for a connection;
Get the status of any connection;
Terminate a connection
AM > SM  Send a message
Retrieve a message
AF > SF  Request to send a file
Allow receipt of a file
Abort file send
______________________________________

User/application Communication

FIG. 18 shows the flow of information tot he user from the various application modules.

Every piece of information conveyed to the user will be through windows on the VGA monitor 16 used as display boxes or as dialog boxes (the latter used also to receive input from the user).

______________________________________
WIN > USER
Actual drawing on the screen of windowed
information;
Menu items used to convey which activities can
be initiated;
AF > WIN  Initiate sending a file (Gives list of files on disk
and their sizes);
File transfer in progress (Shows progress of file
transfer);
Accept receipt of file (Shows remote user's
file name, size, etc.)
AM > WIN  Send a message (Shows message as entered,
allows editing);
Receipt of a message;
AC > WIN  Setup a call (Gives list of names/numbers and
data rates);
Statistics on connections (Up/down, with whom,
data rate, etc.);
Incoming data connection request (Data rate,
bandwidth, name, etc.)
______________________________________

User Generated Events

Turning now to FIG. 19, the flow of user-generated events between modules is illustrated.

______________________________________
USER > WIN
User executes program from Windows which
performs initialization;
Chooses Exit from File menu;
Chooses Connect from Call menu;
Chooses Hangup from Call menu;
Chooses Send file from File menu;
Chooses Send message from Services menu;
Accept incoming connection through dialog box;
Accept incoming file send request through dialog
box:
Deny incoming file send request through dialog
box;
Choose Voice Call off of Menu;
USER > VX User takes phone off-hook;
User puts phone on-hook;
WIN > AW  Call to WinMain( ) to initialize program
Exit request
Connect request
Hangup request
Send file request
Send message request
WIN > AC  Accept incoming connection
Deny incoming connection
WIN > AF  Accept incoming file
Deny incoming file
AW > AI   Initialize resource layer
Clean up resource layer
AW > AC   Connect request
Hangup request
AW > AV   Bring up/down Voice Call Window
AW > AF   Send file request
AW > AM   Send message request
______________________________________

Theory of Operation

When the program begins execution, the Application Layer 50 will initialize itself, and make initiation calls to the Service Layer 80 and the Resource Management Layer 70. Eventually, either the user or the network will initiate a logical connection, followed by requests to do a file transfer, a message send, or to control the phone line. Finally, the logical connection is terminated, and the cycle can begin again, or the program is exited after shutting down each of the layers that had been initialized.

The following sections detail the flow of data and control in a sampling of activities that may be performed during a typical session: initialization, establishing a connection, sending a file, sending a message. In each of these scenarios, the activity begins with the user initiated event, and shows the resulting network initiated events expected on both the subscriber stations 12 and 12'.

______________________________________
Initialization
______________________________________
USER > WIN    User executes program
WIN > AW      WinMain( ) is called, creating main
window
AW > AI       ISDN initialization function is called
DISK > WIN > AI
ISDN config. info. is read from disk via
Windows calls
AI > RA       Application initializes and registers itself
with resource layer
RA > RI       Initializaion request sent to ISDN
interface module
RI > VX       Hardware is finally initialized
______________________________________

Establishing a Connection

It should be noted that each "indented" line represents activity occurring at the subscriber station 12'.

______________________________________
USER > WIN    User selects call setup from connections
menu;
WIN > AW      Call setup request sent to application;
AW > AC       Calls call setup function;
AC > WIN > USER
Displays connection dialog box;
USER > WIN > AC
User sets options, requests connection;
AC > RB       Application requests bandwidth selected
by user;
RB > RI       Request to send connection request
message (X data);
______________________________________

The following could also be implemented utilizing circuit-switched channels or UUI information in a call setup.

______________________________________
RI > VX      Request X25 session;
VX > RI      X25 session request
RI > VX      Accept request
VX > RI      X25 session connected end-to-end;
VX > RI      X25 session connected end-to-end
RI > VX      Send X data (connection request from
RB);
VX > RI      Receives data on connection request
RI > RB      Delivers X data to RB
RB > RB      Give connection request to event router
RB > AI      Deliver request to particular application
AI > AC      Deliver request to connections module
AC > WIN > USER
Display incoming call request
VX > RI      X25 data was sent;
RI > RB > AC Notifies AC that request was sent;
RI > VX      Disconnect X25 session;
VX > RI      X25 session disconnected.
______________________________________

Idle until user responds to incoming call dialog box.

______________________________________
USER > WIN > AC User accepts connection
AC > RB         Connection accept deliver to RB
______________________________________

The bandwidth allocator module, RB, delivers acknowledgement to station 12' via X25 session data (similar to above).

______________________________________
VX>RI   X25 data received;
RI>RB   X data containing acknowledgement of connection;
RB>AC   "Connection is proceeding";
RB>RI   initiate B channel connections
______________________________________

There will be a series of B channel messages (RI>VX, VX>RI) on both sides.

______________________________________
VX>RI      Last B channel connected, ready to send;
RI>RB      Last B channel connected, ready to send;
RB>AC      Connection is established;
VX>RI      Last B channel connected, ready to send
RI>RB      Last B channel connected, ready to send
RB>AC      Connection is established.
______________________________________

Sending A File

______________________________________
USER>WIN>AW>AF User chooses Send File from File
menu, sent to AF module
AF>AC          Get status of current connection
AF>WIN>USER    Display Send File Request dialog box
USER>WIN>AF    User chooses a file to send, "OK"s
send request
AF>SF          Application tells service to send file
SF>RA          Request session ID
SF>RA          Send non-session data; New service
request to send file
RA>RB>RI       Non-session data request sent over
B channels connection
RI>VX          Send data on B channel
VX>RI>RB       Receive data on B channels
connection
RB>AC          Deliver non-session data to
application
AC>AF          New service request: Request to send
file
AF>WIN>USER    Show user `Request to send file`
dialog box
USER>WIN>AF    User `OK's receipt of file
AF>SF          Notify service that we will receive
file
SF>RA          Estabilsh session over B channels
connection
RA>RB>RI>VX    Session connection message sent over
network
VX>RI>RB>RA    Session connection request received,
session now up
RA>SF          Tell service that session is now up
______________________________________

The following lines will occur for each block in the file to be sent.

______________________________________
SF>RA         Request to receive block of file data
RA>RB>IR>VX   `n` number of receives, for each `B`
channel
DISK>SF       Read block of data to be sent
SF>RA>RB      Request to send block of data in buffer
RB>RI>VX      `n` send requests initated
SF>AF>WIN>USER
Show user elapsed time, amount of
file sent
VX>RI>RB      `n` sends completed (queued to be sent)
RB>SF         Notify service that block is queued to
be sent
DISK>SF       Read block of data to be sent
[Cycle to DISK>SF about 7 steps back]
VX>RI>RB      `n` receives complete
RB>SF         Notify service that a block of data was
received
SF>DISK       Write data block to disk
SF>RA         Request to receive block of file data
SF>AF>WIN>USER
[Cycle back to SF>RA at top]
DISK>SF       Failure on disk read, file send is
therefor complete
SF>RA>RB      Request to drop connection
SF>RA>RB      Send request to drop connection on
remote side
VX>RI>RB      Receive connection drop message
RB>RA>SF      Tell service that connection has been
dropped
SF>DISK       Close file
SF>AF         Notify application that file has been
received
AF>WIN>USER   Notify user; send complete; show
elapsed time
SF>AF>WIN>USER
Notify user that send is complete; show
elapsed time
______________________________________

Sending A Message

______________________________________
USER>WIN>AW>AM User chooses Send Message from
menu
AM>AC          Get status of current connection
AM>WIN>USER    Display Send Message Request
dialog box
USER>WIN>AM    User enters message, chooses `SEND`
AM>SM          Application tells service to send
message
SM>RA          Send non-session data: New message
(w/text)
RA>RB>RI       Non-session data request sent over B
channels connection
RI>VX          Send data on B channel
VX>RI>RB       Receive data on B channels
connection
RB>AC          Deliver non-session data to
application
AC>AM          New message request (w/text)
AM>SM          Tell service that message is in, SM
saves text
AM>SM          In foreground, retrieve message text
to display
AM>WIN>USER    Display message for user to view
______________________________________

Directory Structure

In the preferred embodiment, all Teleos software will be in its own directory (I.E. C: B101 ). This includes NETBIOS.EXE, BSTART.EXE, download files, etc.

Similarly, all HSDT related files will be in a separate directory (i.e. C: WIN3 ). The HSDT related files include:

______________________________________
PCTA.BAT - Load Teleos runtime software and load
RTELEOS.EXE
RTELEOS.EXE - TSR to support VX module.
HSDT.EXE - High Speed ISDN Data Transfer software package.
NAMES.DAT - Names and Numbers database.
WIN.INI - Configuration information for HSDT.EXE
______________________________________

Vendor Layer Modules

In the preferred embodiment, the Teleos B101PC Terminal Adapter is the ISDN hardware. The code in the Vendor API Layer 50 will utilize the Teleos API for communicating with each TA. It will also present an interface to the Resource Management Layer 70 that is independent of the Teleos API. This will allow future versions of the software to make use of other hardware, such as DGM&S IDC.

Vendor Specific (VX) Module

Purpose:

Isolate vendor-specific code to a small piece of replaceable software. It will accomplish the following: send and receive on `B` channels, X.25 sessions with another node, and voice control.

Description:

This module drives a specific vendor's ISDN (e.g. Basic Rate Interface) hardware. This implementation will drive Teleos B101PC TAs 24 through the ASK-100 API. It then presents to the Resource Management Layer 70 a standard interface such that a replacement of this module for another vendor will not require changes to the interface.

__________________________________________________________________________
Data Structures:
typedef void    VXT-- Post //
Callback with VXM-- messages
( void *xArgs, int msg,
word wParam, long lParam);
typedef VXT----BStruct
*VXT-- BHan;
typedef struct vxt-- bstruct
VXT--BStruct;
typedef struct vxt--bstat
VXT--BStat;
struct vxt-- bstruct
{
int  card
VXT-- Post
*post,
void  *xArgs,
uint  flags,
// SEND or RECV -- PEND/-- CMPLT/-- CLR
// Specific info needed to drive teleos interface
void  *sendP,
// Buffer pointers may not be needed
int   sendLen,
void  *recvP,
int   recvLen,
byte  sess,
VTT-- Ncb
nSend,
// Sends to DPP, even start msgs
VTT-- Ncb
nRecv,
// Receives from DPP
};
struct vxt-- bstat
{
int  state
// VXC-- NEEDINIT/-- STARTED/
-- ENDTOEND/-- DISCON
struct vxt-- card
{
// Voice/phone
// D channel and X.25
VXT-- BStruct b[ 2];
// B channel info
};
Public Interface:
Prototypes for Whole card control functions:
int  VX-- Setup(
int cn):     // Card number (0 to VXK-- NCARDS- 1)
int  VX-- Cleanup)
int cn):     // Card number
#if defined ( TCX-- POLL)
int  VX-- Poll(
int cn):
// Card number
#else
#define
VX-- Poll (cn):
// No Polling
#endif
int  VX-- VAction(
int cn,      // Card Number
byte *dial,  // Null terminated string
int button,  // 0=None, 1-63 CA/FEAT# OxFO-3 H,D,T,C
int hook);   // 0=None, 1=On, 2=Off
Prototypes for `B` channel control/send/recv functions
int  VX-- BSetup(
int        cn,  // Card number
byte       ph[],
// Phone number to connect to
uint       cap, // Requested capability VXP-- BC-- any
VXT-- Post
*postF,
// User post function
void       *xArgs,
// User arguments to user post function
VXT-- BHan
*bh);
// Rtn: handle on a `b` channel
int  VX-- BAccept (
int        cn,  // Card number
void       *inMsg,
// 1parm from incall message indication
VXT-- Post
*postF,
// User post function
void       *xArgs,
// user arguments to user post function
VXT-- BHan
*bh);
// Rtn: handle on a `b` channel
int  VX-- BReject(
int        cn,  // Card number
void       *inMsg,
// 1Parm from incall message indication
int        reason);
// User defined reject reason (0..63)
int  VX-- BCleanup(
VXT-- BHan
bH); // Handle on the `b` channel
int  VX-- BSend(
VXT-- BHan
bH,  // Handle on the `b` channel
int        len, // Length of following buffer
void       *buf);
// Points to user's buffer
int  VX-- BRecv(
VXT-- BHan
bH,  // Handle on the `b` channel
int        len, // Length of following buffer
void       *buf);
// Points to user's buffer
int  VX-- BStatus(
VXT-- BH an
bH,  // Handle on the `b` channel
VXT-- BStat
*s); // Returns pointer to statistics/status
Prototypes: X channel control/send/recv functions
int VX-- XSetup(
int        cn,  // Card number
byte       ph[],
// X.25 address to connect to
uint       cap, // Requested capability
VXT-- Post
*postF,
// User post function
void       *xArgs,
// User arguments to user post function
VXT-- XHan
*xH);
// Rtn: handle on a `x` session
int  VX --XAccept(
int        cn,  // Card number
void       *inMsg,
// 1Parm from incall message indication
VXT-- Post
*postF,
// User post function
void       *xArgs,
// User arguments to user post function
VXT-- XHan
*xH);
// Rtn: handle on a `x` session
int  VX-- XRegect(
int        cn,  // Card number
void       *inMsg,
// 1Parm from incall message indication
int        reason):
// User defined reject reason (0..63)
int  VX -- XCleanup(
VXT-- XHan
xH,  // Handle on the `x` session
int  VX-- XSend(
VXT-- XHan
xH,  // Handle on the `x` session
int        len, // Length of following buffer
void       *buf);
// Points to user's buffer
int  VX-- XRecv(
VXT-- XHan
xH,  // Handle on the `x` session
int        len  // Length of following buffer
void       *buf);
// Points to user's buffer
int VX-- XStatus(
VXT-- XHan
xH   // Handle on the `x` session
VXT-- XStat
*s); // Returns pointer to statistics/status
__________________________________________________________________________

Vendor Specific Events

All events are delivered as messages with customized wParam and 1Param values. See VXM_-- any defines and comments. The user's function must be prepared to be called from within an interrupt function (i.e. asynchronously). The xArgs parameter is defined by the user, and specified at the same time the callback function pointer was passed (see VX_-- Setup, VX_-- BAccept, VX_-- XSetup, VX_-- XAccept function params). Note, in the preferred embodiment, callback functions MUST NOT make calls to the VX interface that result in a WAIT mode request, or that make DOS calls (these are: Setup, Cleanup and Accept functions).

______________________________________
void-- far VX-- Callback(
void   *xArgs,  // User arguments are passed back to user
int    msg,     // The message; VXM-- any
word   wParam,  // Single word argument; message specific
long   1Param); // Single long argument; message specific
B messages:
VXM-- BCALL
Received after VX-- Setup( ).
Indicates that an incoming `b`
channel connection request was
received from the ISDN network.
wParam is the card number.
1Param contains a vendor specific
value that must be returned to
VX-- BAccept( ) or
VX-- BReject( ) commands in the
imMsg parameter field.
X messages:
VXM-- XCALL
Received after VX-- Setup( ).
Indicates that an incoming `x`
session connection request was
received from the ISDN network.
wParam is the card number.
1Param contains a vendor specific
value that must be returned to
VX-- XAccept( ) or
VX-- XReject( ) commands in the
`imMsg` parameter field.
Voice messages:
VXM-- VHOOK
Generated whenever a change
is detected in Hook state (phone on
or off hook) wParam: new hook
state 1=on; 2=off 1Param: OL
VXM-- VSCA Generated whenever a change
is detected in Selected call
appearance wParam: new sca;
1Param OL
VXM-- VCA  Generated whenever a change
is detected in Call/feature buttons
wParam: 0; 1Param: byte ca-- stat
[64]
VXM-- VINFO
Teleos level struct indications, per
wParam:
VXW-- STAT-- IND
Status indication.
1 Param:
VTT-- V-- StatInd -- far *
VXW-- INFO-- Ind
Info indication.
1Param:
VTT-- V-- InfoInd -- far *
VXM-- VST-- CA
Change in state of call Appearance
wParam: ca#; 1Param:state (per
CCITT Q.931)
VXM-- VST-- FEAT
Change in state of Feature
Appearance wParam: button#;
1Param:state (per CCITT Q.931)
VXM-- VPROG
Progress indicator. wParam: pi#
(per CCITT Q.931); 1Param: 0
VXM-- VCAUSE
Cause code. wParam: cause#
(per CCITT Q.931); 1Param: 0
VXM-- VDISP-- CONTEXT
Preceeds display items.
wParam: ca#; 1Param: mode (per
AT&T 5ESS spec)
VXM-- VDISP-- ITEM
Display items (per CONTEXT).
wParam: type (per AT&T 5ESS
spec); 1Param: char -- far *text;
B messages:
VXM-- BSEND
Received after VX-- BSend( ). User
must not disturb the send buffer
until this message is received. This
message means that the send-buffer
data has been queued to be sent. It
does not means that the data has
actually been delivered. wParam
and 1Param are both zero.
VXM-- BRECV
Received after VX-- BRecv( ).
Unless the VX-- Brecv( ) command
is given, no data will be received
on this channel. This command
allows the VX module to make a
request to receive. The buffer must
not be disturbed until this message
is received. This message is an
indication that the receive request
is complete and the receive buffer
contains data. The actual length of
received data must be determined
through a VX-- BStatus( ) call.
Both wParam and 1Param are zero.
VXM-- ENDEND
Received after VX-- BSetup( ) or
VX-- BAccept( ). This message
indicates that an end-to-end connec-
tion exists, but the DPP process to
maintain an actual data channel
connection is not yet present for
this `b` channel. User may not
not yet perform VX-- BSend( ) and
VX-- BRecv( ) commands. The
DPP may take up to seven seconds
to be started. Both wParam and
1Param are zero.
VXM-- BCONN
Received after VX-- ENDTOEND
message. This message indicates
that a complete connection (end-to-
end as well as a DPP process to
maintain actual data channel
connection) is now present for this
`b` channel. User may now perform
VX-- BSend( ) and
VX-- BRecv( ) commands. Both
wParam and 1Param are zero.
VXM-- BFAIL
Received only on a `b` channel
that has not yet been
VXM-- BCONNected. wParam
gives the reaon (VXU-- any).
1Param is zero. User must
eventually call VX-- BCleanup( ) to
free up the resources allocated to
this channel.
VXM-- BDISCON
Received only on an existing `b`
channel that has been
VXM-- BCONNected. wParam
gives the reason (VXU-- any).
1Param is zero. User must
eventually call VX-- BCleanup( ) to
free up the resources allocated to
this channel.
X messages:
Messages posted to postF in VX-- XSetup( ):
VXM-- XSENT
Received after VX-- XSend( ). Only
one send may be pending per X25
interface (i.e. per card).
wParam: 0 or Vendor error;
1Param: xH
VXM-- XRECV
Data has been received on an
established link; wParam: length
(0..VXK-- MAX-- XDATA);
1Param: Data pointer
VXM-- XREADY
Received after VX-- XSetup ( ) and
during VX-- XAccept( ). Indicates
link is established. User may now
perform VX-- XSend( ) and
VX-- XRecv( ) commands.
wParam: sess#; 1Param: xH
VXM-- XFAIL
Received only on initiating side,
before XREADY message
wParam: cause (per CCITT X.25
rec.); 1Param: xH
VXM-- XDISCON
Received only after
VXM-- XREADY on
established link.
wParam: cause (per CCITT X.25
rec.) 0=normal; 1Param: xH
______________________________________

Resource Management Layer Modules

To support the Service Layer 80, the ISDN lines 26 must be managed (linked and synchronized) as a shared resource. Thus, the `B` channels are managed as a resource, to ensure a cooperative use of ISDN hardware. Features of the Resource Management Layer 70 include:

call setup for a Voice connection without interrupting an existing logical connection. Once a voice connection is established, a voice features service can be attached to it; and

call setup for a Data connection by specifying a bandwidth allocation and a main phone number. This layer must deal with the detail of dialing various phone numbers associated with more than one BRI line 26 at each site. Once this logical connection is established, the Resource Layer 70 must allow several services to connect with its resource counterpart, on this single connection.

Asynchronous events, as described in greater detail above, must be routed to the application so that it may define the method for dealing with asynchronous activity within its defined user interface environment. Each event should be associated with its respective data or voice connection. Future capabilities might allow for an X.25 type connection to the remote station at the Application/Service Layer.

ISDN Configuration Management (RI) Module

Purpose:

Presents to rest of layer: Some number of `B` channels, Voice control of a single phone, and X.25 connection with another node (id: data path to another node with out use of a `B` channel)

Description:

Supports these actions:

Bandwidth allocation/connection;

Availability and status;

Voice capability;

Network messages;

Negotiation (Allow discussion with other side)

Isolates rest of code from knowing:

Which D channel goes with which B channel;

Keeping a voice channel open where possible;

Where Phone is (which device its plugged into);

Specific card's phone numbers locally and remotely;

Nature of an X.25 session;

Matching similar B channel capabilities with remote side;

______________________________________
Data Structure:
struct rit-- bstruct
byte       crx;    //Centrex prefix
char       ph [ RIK-- PH-- LEN];
int        state;  // UP/DOWN/Other
struct rit-- ustruct
{
int        ra;
char       rPh [ RIK-- PH-- LEN];
int        state;
int        err;     // XV error within post funcs
RIT-- Post -- far
*postF;  // Callback function pointer
void   -- far
*xArgs;  // Callback user args
int        rLen;    // Recv length (for restarts)
VXT-- BRecv-- far
*rBuf;   // Recv buffer (for restarts)
int        cn;      // Card number
RIT-- BStruct/far
*bs;     // Points to B struct
VXT-- BHan
bH;      // Vendor layer handle
};
struct rit-- card
{
int        cn;   // Card number
RIT-- BStruct
b [ RIK-- BPERC];
};
struct rit-- xtalk
{
HANDLE     xtH;     // Windows handle to this
struct
HANDLE     nextH;   // Windows handle to next
struct to send
char       ph       // Address to send data to
[RIK-- PH-- LEN];
int        len;     // Length of user data
byte       buf      // Malloced area for data
[ 2];
};
struct rit-- xstruct
// Information to manage X25
send/recv
{
int        state;   // IDLE/READY/START/
ACCPT/ExpectACCPT
int        len;     // Total length
int        sLen;    // Length sent so far
VXT-- XHan
h;       // Handle on Vendor layer x25
int        err;     // Final errors if any
struct rit-- ri
{
RIT-- Card
c [ RIK-- NCARDS-- MAX];
RIT-- UStruct
u [ RIK-- UCHANS-- MAX];
int        nC;      // Number of cards (from setup)
int        nU:      // Number of user channels
2*ncards?
RIT-- Post -- far
*postF;
void   -- far
*XArgs;
int        state;   // State of module
// X.25 Session control
RIT-- XStruct
xS;      // Send on x25
RIT-- XStruct
xR;      // Receive on x25
RIT-- XTalk -- far
*xtS;    // Que of x25 messages to be
sent
int        xLen;    // Size of receive buffer
byte  -- far
*xBuf;   // Buffer for receiving an x25
};
Public Interface:
Return values:
RIE-- ALLOC
// Could not allocate needed memory
RIE-- NOBCHAN
// No `B` chans available
RIE-- NOBCHAN
// Connection is down or invalid handle
int RI-- Setup(
//Initialize the ISDN hardware and this module
// Number of cards
// Local phone number for each `B` chan per card
// # X sessions (# listening and # total)
// Buffer area for each X receive
int RI-- XSend(
// Send X data (data-gram sent using X
sessions)
// Phone number
// Length of data to send
// Pointer to data
int RI-- Alloc(
// Allocate `B` chan
// Rate adaptation (RIP-- Rany (64R, 64UR, 56UR)
// CallBack func for this connection
// User args
// Rtn: Handle on `B` chan (Hb)
int RI-- ReAlloc(
// Reallocate resources (change rate adapt.)
// Handle on `B` chan (Hb)
// New rate adaptation (RIP-- Rany (64R, 64UR,
56UR)
int RI-- Conn(
Request connection to remote `B` chan
// Handle on `B` chan (Hb)
// Phone number
int RI-- Close(
// Close a conenction, dealloc resources
// Handle on `B` chan (Hb)
int RI-- Stat(
// Retrieve statistics on a connection
// Handle on `B` chan (Hb)
// Rtn: phone number
// Rtn: remote phone number connected to
// Rtn: Rate adapt, etc.
int RI-- Send(
// Send data across a bandwidth connection
// Handle on `B` chan (Hb)
// Length of data to send
// Pointer to data buffer
int RI-- Recv(
// Start async receive request
// Handle on `B` chan (Hb)
// Length of destination buffer
// Pointer to destination buffer
Resource Management Layer Events:
RIM-- XDATA
// Received X data (w/buffer number)
RIM-- VOICECHG
// Change in voice state (w/new state vals)
RIM-- START
// Starting `B` chan connect
RIM-- READY
// Connection connected, ready to
send/recv
RIM-- DOWN
// Connection is down (w/reason)
RIM-- RECV
// Data `receive` completed on `B` chan
RIM-- SENT
// Data `send` completed on `B` chan
Bandwidth Allocation (RB) Module
Purpose:
The RB module manages groups of B channels to
be presented to the HSDT software as a single
logical connection.
Data Structures:
struct rbt-- pipe
{
int       state;   // Control on per `pipe` basis
byte      bufs     // Send/Recv pipe buffers
[ RBK-- B-- MAX]
// For each `b` channel
in bandwidth
[ size of { RBT-- RIsr)];
};
struct rbt-- con
{
int       nB;      // Number of `B` channels in
this connection
int       ra;      // Rate adaptation
int       nSb;     // Number of SEND buffer sets
(pipes)
int       nRb;     // Number of RECV buffer sets
(pipes)
int       bSz;     // Size of a B chan buffer
RBT-- Post -- far
*postF;  // User post func
void   -- far
*xArgs;  // User args
int       state;   // State of connection
int       err;     // Error from lower layers
int       eB;      // `B` channel with lower layer
error
unsigned  upF;     // Bit flags: `B` chans that
are up and ready
unsigned  sF;      // Bit flags: `B` chans that
completed `send`
unsigned  rF:      // Bit flags: `B` chans that
completed `recv`
QU-- WDStruct( rbt-- que, int)
q;       // Que of pipes that are ready
to be sent
int       sState;  // Send state
int       rState;  // Recv state
HANDLE    sH;      // Windows HANDLE on sP
RBT-- Pipe -- far
*sP;     // Points to array of `pipe's
(SEND)
HANDLE    rH;      // Windows HANDLE on rP
RBT-- Pipe -- far
*rP;     // `pipe's (RECV)
int       pS;      // Pipe number that is SENDING
int       pR;      // Pipe number that is RECVING
RIT-- UHan
uH       // RI layer handles
[ RBI-- B-- MAX];
struct rbt-- args
// xArgs sent to RI layer for
RB callback
{
int       b;       // `B` channel number
RBT-- CHan
cH;      // Points back to master
RBT-- Con struct
]         args     // xArgs to RI layer
[ RBK-- B-- MAX];
};
Public Interface:
Return values:
RBE-- ALLOC
// Could not allocate needed memory
RBE-- BCHANS
// Not enough `B` chans available
RBE-- DOWN
// Connection is down or invalid handle
RBE-- NODATA
// Receive buffer has no data
Functions:
int RB-- Alloc(
// Allocate connection resources
// Bandwidth (# of `B` chans)
// Rate adaptation (RBP-- Rany (64R, 64UR, 56UR)
// CallBack func for this connection
// User args
// # of send buffers
// # of recv buffers
// Size of one `B` chan buffer
// Rtn: Handle on connection (Hc)
int RB-- ReAlloc(
// Reallocate resources (Drop/add `B` chans)
// Handle on connection (Hc)
// New bandwidth (# `B` chans)
// New rate adaptation (RBP-- Rany (64R, 64UR, 56UR)
int RB-- Conn(
// Request connection to many `B` channels
// Handle on connection (Hc)
// List of Phone numbers, one for each `B` chan
int RB-- Close(
// Close a connection, dealloc resources
// Handle on connection (Hc)
int RB-- Stat(
//Retrieve statistics on a connection
// Handle on connection (Hc)
// Rtn: list of phone numbers, one for each `B` chan
// Rtn: list of remote phone numbers connected to
// Rtn: number of `B` chans, Rate adapt, etc.
int RB-- Send(
// Send data across a bandwidth connection
// Handle on connection (Hc)
// Length of data to send
// Pointer to data buffer
int RB-- GetData(
// Retrieve data that is waiting in a buffer
// Handle on connection (Hc)
// Handle on source buffer for connection (from
RBM-- RECV msg)
// Length of destination buffer
// Pointer to destination buffer
Events:
RBM-- START    // Starting to build `B` chan
connections
RMB-- READY    // Connection connected, ready to
send/recv
RBM-- DOWN     // Connection is down (w/reason)
// RBM-- RECV/-- SENT
give handle on connection +
buffer handle
RBM-- RECV     // Data was received on bandwidth
connection
RBM-- SENT     // Data was sent
______________________________________

Application Interface (RA) Module

Description:

Provides an interface to service applications:

Voice connection;

Voice commands;

Status/Equipment list;

Data connection;

Data send/receive (Block or message);

Network messages (Asynchronous);

Establish multiple sessions over same data connections;

Accomplishes the following:

Allows multiple sessions over dame data connection;

Synchronize requests from more than one application/service (or instance of such);

Sharing of ISDN resources;

Delivery of network messages to correct applications;

______________________________________
Data Structures:
struct rat-- coreq
// Structures send across the
X25 link
{    t;              // Type: RAC-- XT--
REQ/REJ/ACK
int  co;             // Connection number to respond
to
int  sync;           // To match REQ/ACK/REJ
pairs
char ph[ RAK-- PH-- LEN];
// Phone number to call back on
char nm[ RAK-- NM-- LEN];
// Name of remote application
int  ra;             // Suggested rate adaptation
int  bw;             // Suggested number of channels
char bPr[ PAK-- BPR-- LEN];
// B-Chan trunc access prefix
char coPh[ RAK-- BPERCO] [RAK-- PH-- LEN];
// Num-
bers for
each chan
int  len;            // Length of request message
char data[ RAK-- TDATA-- LEN];
// User request message
};
struct rat-- se
RAT -- Post -- far
*postF;  // Call back function
void   -- far
*xArgs;  // Call back user args
int         state;   // Up/Down/Free/Other
byte        rSe;     // `Return` session number to
remote
byte        co;      // Index to associated
CONNECTION struct
byte        sync;    // For matching sessions on
each end
struct rat-- co
{
RAT-- Post -- far
*postF;  // Callback
void   -- far
*xArgs;  // Callback user args
char rPh[ RAK-- PH-- LEN];
// Remote phone that we're
connected to
int         state;   // Up/Down/Errored/Waiting/
Other
int         sync;    // To match REQ/ACK/REJ
pairs
HANDLE      reqH;    // Saved request struct
HANDLE
RAT-- CoReq -- far
*req;    // Saved request struct til
ACK/REJ
RAT-- Sb sb[ RAK-- NPIPES];
// Send buffer stats
RBT-- CHan
hRB;    // RB Module handle
};
struct rat-- ap
{
char nm[ RAK-- NM-- LEN];
// Application name
RAT-- Post -- far
*postF;  // Post function
void   -- far
*xArgs;  // Post user args
int         state;   // Free/Inuse
};
struct rat-- ra
{
int  state;
char cxBufR[ RAK-- XLEN];
// X.25 buffer for RI recvs
RAT-- Ap
ap[ RAK-- NAPPS];
// Applicaton structs
RAT-- Co
co[ RAK-- NCONS];
// Connection structs
RAT-- Se
se[ RAK-- NSESS];
// Session structs
int     sync;         // Synchronizing value
};
Public Interface:
Return Values:
RAE-- ALLOC
// Could not allocate needed memory
RAE-- NOBCHAN
// No `B` chans available for
connection
RAE-- CODOWN
// Connection is down or invaild
handle
RAE-- SEDOWN
// Session is down or invalid handle
Setup/Registration Functions:
int RA-- Setup(
// Initialize the ISDN hardware and this module
// Number of cards
// Local phone number for each `B` chan per card
// Indication of whether to deal with voice messages
Int RA-- AppReg(
// Register application by name
// Name of application
// Callback func for connection requests
// User args
// Rgn: Handle for this application (Ha)
int RA-AppDereg(
// De-register the application
// Handle for this application (Ha)
int RA-- Cleanup(
Un-init the module (and hence the ISDN
hardware)
// no parameters
Connection oriented functions:
int RA-- CoReq(
// Request connection to remote
application
// Handle for this application (Ha)
// Main phone number of remote application
// Name of remote application
// Length of user data
// User data (application defined request message)
// Suggested Rate adaptation (RAP-- Rany (64R,
64UR,   56UR)
// Suggested number of `B` chans (bandwidth)
// CallBack func for this connection
// User args
// Rgn: Handle on connection (Hc)
int RA-CoAckReq(
// Acknowledge connection to remote
application
// Handle for this application (Ha)
// Param from RAM-- COREQ message
// Final Rate adaptation (RAP-- Rany (64R, 64UR,
56UR)
// Final number of `B` chans (bandwidth)
// CallBack func for this connection
// User args
// Rtn: Handle on connection (Hc)
int RA-- CoRejReq(
// Reject a connection to remote
application
// Handle for this application (Ha)
// Param from RAM-- COREQ message
// reason
// Length of user data
// User data (application defined reject message)
int RA-- CoClose(
// Close a connection, dealloc resources
// Handle on connection (Hc)
int RA-- CoStat(
// Retrieve statistics on a connection
// Handle on connection (Hc)
// Rtn: local phone number
// Rtn: remote phone number connected to
// RTN: Rate adapt, # `B` chans, connected state, etc.
int RA-- CoSend(
// Send data across a connection w/o
session ID
// Handle on connection (Hc)
// Length of data to send
// Pointer to data buffer
// Rtn: actual length of data that was buffered to be
sent
int RA-- CoGetData(
// Retrieve incoming non-session data
// Param from RAM-- CORECV message
// Length of destination buffer
// Pointer to destination buffer
// Rtn: actual length of received data
Session oriented functions:
int RA-- SeReq(
// Request connection to remote
application
// Handle for this application (Ha)
// Length of user data
// User data (application defined request message)
// CallBack func for this session
// User args
// Rtn: Handle on session (Hs)
int RA-- SeAckReq(
Acknowledge request for connection
// Handle for this session (Hs)
// Param from RAM-- SEREQ message
// CallBack func for this connection
// User args
// Rtn: Handle on session (Hs)
int RA-- SeRejReq(
Reject connection to remote
application
// Handle for this session (Hs)
// Param from RAM-- SEREQ message
// reason
// Length of user data
// User data (application defined reject message)
int RA-- SeClose(
// Dispose of session ID within a
connection
// Handle for this sessin (Hs)
int RA-- SeSend(
// Send data across a connection using a
session ID
// Handle for this session (Hs)
// Length of data to send
// Pointer to data buffer
// Rtn: actual length of data that was buffered to be
sent
int RA-- SeGetData(
// Retrieve incoming session data
// Handle for this session (Hs)
// Length of destination buffer
// Pointer to destination buffer
// Rtn: actual length of received data
Events:
RAM-- COREQ
// Request for connection from remote side
RAM-- COACK
// Received acknowledgement, starting to
connect
RAM-- COREJ
// Received rejection (w/reason)
RAM-- COREADY
// Connection ready to send/recv
RAM-- CODOWN
// Connection is down (w/reason)
RAM-- CORECV
// Non-session data has been received
RAM-- COSENT
// Non-session data has been sent
RAM-- SEREQ
// Request for session coming from remote
side
RAM-- SEACK
// Received acknowledgment, starting to
connect
RAM-- SEREJ
// Received rejection (w/reason)
RAM -- SEREADY
// Session ready to send/recv (remote
connected)
RAM-- SEDOWN
// Session is down (w/reason)
RAM-- SERECV
// Session data has been received
RAM-- SESENT
// Session data has been sent
______________________________________

Service Layer Modules

The Service Layer 80 is made up of a plurality of actal `services` modules that can be mixed and matched for the specific application, where the HSDT software, being implemented. These services should be written to take advantage of the Resource Management Layer 70 for the cooperative use of the ISDN hardware. Services should also be written to allow several instances of themselves to exist where more than one application may be running, or more than one instance of a service may be required by a single application.

In the preferred embodiment, each service is actually written in two parts which are the `initiating` and `responding` sides of a logical connection between the same service on each side of the connection. This client/server model will dominate a description of each of the services to follow.

File Transfer (SF)

Purpose:

The SF module performs the File transfer function through utilization of the Resource Management Layer 70.

Description:

Using a file name and a reference to an established data connection, performs a transfer negotiation phase where each subscriber station 12 must agree between themselves that the transfer is to take place and after exchanging some statistics about the size of the file and anticipated duration the transfer is allowed to proceed as described in greater detail. A high speed disk intensive file transfer algorithm will transfer blocks of the file to the realization of the full bandwidth available on the given logical connection. Ongoing progress of the transfer process will be made available to the HSDT software.

______________________________________
Data Structures:
struct sft-- srv
// Given by user
char       file [ SFK-- FILE-- LEN];
SFT-- Post -- far
*post F; // Callback
dword      xArgs;   // Callback user args
int        pipes;   // Number of RB Module pipes to
fill
int        block;   // Size of RA Send blocks per
channel
int        ackCnt;  // Acknowledge counter for
handshaking
// Calculated once
int        bw;      // Bandwidth in # channels
long       fLen;    // Length of file
int        io;      // File handle after open ( )
clock-- t
sTicks;  // Start ticks value
// Forever changing
int        state;   // Sending/Wait for ACK/Done/
Abort
int        blkCnt;  // Number of blocks sent/recved
long       aLen;    // Active length (recv/sent so
far)
int        pFree;   // Number of free send pipes
clock-- t
fTicks;  // Final ticks value
// Misc handles on stuff
HANDLE     fHH;     // Windows handle on open file
RAT-- SeHan
seH;     // Resource layer session
handle
// Disk buffer management
HANDLE     dHan;    // Windows handle
SFT-- DPtr -- far
*dPtr;   // Locked pointer
int        dTran;   // Disk transfer size
int        dPipe;   // Size of a pipe
int        dDate;   // Amount of data bytes
currently in buf
byte  -- far
*dAvail; // Points to avail space
(dPtr+dData)
int        dEOF;    // Flag that end of file was
reached
};
struct sft-- req
{
byte       srvId;   // User defined service ID to
link SERVICES
char       file[ SFK-- FILE-- LEN];
int        block;   // Size of one block
int        ackCnt;  // Acknowledge counter
long       fLen;    // File length
long       ticks;   // Estimated 1000ths of seconds
int        kbps;    // Bandwidth
int        bLen;    // Length of following buffer
char       buf[ 2]; // Must pad with user's real
length
};
Reasons for rejection:
SFP-- RSIZE
// File is too big to save on local disk
SFT-- RTIME
// Send will require too much time
SFT-- RMONEY
// Cannot afford to do send this time of day
SFT-- RCOPY
// Already have a copy of this file
SFT-- RDAY
// Would like to receive file later in day
SFT-- RWEEK
// Would like to receive file later in week
SFT-- RMONTH
// Would like to receive file later in month
SFT-- RNUMBER
// Number of files being sent is too much
SFT-- RNEWER
// Would like a newer version / mine is
newer
SFT-- RNONE
// No particular reason
Public Interface:
int SF-- SendReq(
// Make a request to send a file
// Handle on a connection (Hc)
// Name of file to be sent
// Callback function to receive statistics
// User args
// Rtn: Handle on the file send service (Hf)
int SF-- AckSendReq(
// Acknowledge request to send a file
// Param from RAM-- SEREQ message
// Name of file on local disk to be created
// Callback function to receive statistics
// User args
// Rtn: Handle on the file send service (Hf)
int SF-- RejSenReq(
// Reject request from remote to send a
file
// Param from RAM-- SEREQ message
// reason (SFP-- Nany)
int SF-- Abort(
// Stop sending the file, destroy the
service
// Handle on the file send service (Hf)
int SF-- Stat(
// Retrieve statistics on file send
// Handle on the file send service (Hf)
// Rtn: length of file, file name
// Rtn: remote's phone number
// Rtn: amount of file sent so far
// Rtn: elapsed time so far, estimated total time
to send
File Transfer Events:
SFM-- ACK
// Service acknowledged, beginning send
SFM-- REJ
// Send was rejected by remote
(w/reason)
SFM-- ABORT
// Remote aborted (w/reason)
SFM-- ERROR
// Low level error on session, service
gone
SFM-- END
// End of file, service is now gone
______________________________________

Message Send (SM) Module

Purpose:

The SM module performs messaging functions through utilization of the Resource Management Layer 70.

Description:

In an ad-hoc manner, a single buffer of text is sent from a first subscriber station 12 over an established logical connection and appears in a buffer on a second subscriber station 12'. By polling or by an asynchronous message, the HSDT software receives this buffer of text. Int he preferred embodiment, this process can take place even during a file transfer on the same logical connection.

______________________________________
Public Interface:
Return values:
SMR-- OK
// No error
SMR-- NOMSG
// There is no message text to be retrieved
SMR-- GETMSG
// There is message text that needs retrieving
Functions:
int SM-- SendMsg(
// Send a message to a remote application
// Handle on a connection (Hc)
// Length of message
// Pointer to message
int SM-- Event(
// Handle incoming SM module
RAM-- SEREQ message
// Param from RAM-- SEREQ message
// Rtn: Handle used to retrieve message text (Hm)
int SM-- GetMsg(
// Retrieve received message text
// Handle used to retrieve message text (Hm)
// Rtn; length of message
// Rtn: Remote's phone number
// Rtn: message text
______________________________________

Message Send Events

None.

Voice (SV) Module

Purpose:

Perform voice functions through utilization of the Resource Layer 70.

Description:

Physical use of an analog phone attached to the PC's ISDN card causes events to occur in software which inform this service of the current hook and voice state of the phone. These events are passed up to the Application Layer 50 for processing.

______________________________________
Data Structures:
None required.
Public Interface:
void FAR SV-- Event(
DWORD dsUserArg,
// User arguments to be
passed
int iMsg,       // Event message
WORD wParam,    // Additional event
information
long lParam);   // Additional event
information
Events:
RAM-- VHOOK
//Phone went physically on/off
hook
RAM-- VSCA //ISDN selected call appearance
changed
RAM-- VST-- CA
//ISDN call appearance state
changed
RAM-- VST-- FEAT
//ISDN feature appearance state
changed
RAM-- VDISP-- CONTEXT
//Context in which to display text
items
RAM-- VDISP-- ITEM
//Text items to be displayed
______________________________________

Database Layer Modules

These modules allow access to ISDN type databases. In the preferred embodiment, only a Name and Phone number database is being utilized.

Name and Number (DN)

Purpose:

The DN module allows access to a list of Names and Numbers, either by returning a Name given a number, or returning a list of all names and numbers.

Description:

Sometimes the HSDT software requires the Name associated with an incoming number. Other times a list is needed of all possible Names that can be called, so the user can choose one. This module retrieves this information from a disk file that has been built before running the software.

______________________________________
Data Structures:
struct DNS-- NAMENUM
char cName[DNC-- MAX-- NAME];
// Name of person /
station
char cNum[DNC-- MAC-- NUM];
// Phone number
];
Public Interface:
Field Sized:
# define
DNC-- MAX-- NAME
64
# define
DNC-- MAX-- NUM
16
Return Values:
# define
DNR-- NOERROR
0
# define
DNR-- NONUM
(-1)
# define
DNR-- NOMORE
(-2)
int DNN-- GetName(
// find a name for the given number
char *sNum,
// passed: number to use to locate name
char *sName);
// return: name associated with number
int DN-- GetFirst(
// get first name & number entry in
database
char *sNum,
// return: number of first entry
char *sName);
// return: name of first entry
int DN-- GetNext(
// get next name & number entry in
database
char *sNum,
// return: number of next entry
char *sName);
// return: name of next entry
______________________________________

Name and Number Events

None.

Application Layer Modules

The core of the HSDT software is written in a manner such that it is independent of any particular user interface. This allows for multiple instances of services to run simultaneously from several applications. These applications may run in a number of environments, including Microsoft Windows, DESQview, DOS TSR, etc.

As previously noted, the HSDT software utilizes Microsoft Windows. This application allows the use of all of the existing services in different windows. Each of the capabilities (Call Setup, File Transfer, Messaging, Voice) exist in separate windows.

As described in greater detail above, each of the features exist in their own child window with appropriate edit prompts and dialog box controls.

Windows Main (AW) Module

Purpose:

The AW module provides program initialization functions and process messages for the main program window.

Description:

As known, any program that runs under the Microsoft Windows environment is required to be structured differently from a traditional `C` program. One difference is that the required function is called WinMain() instead of main(). Also, Windows applications must make use of the message-based architecture of execution instead of traditional top-down programming.

______________________________________
Data Structures:
extern HANDLE g-- hInst;
// handle to program instance
extern HWND g-- hFrameWnd;
// handle to frame window
extern HWND g-- hClientWnd;
// handle to MDI client
extern HANDLE g-- hAccTable;
// handle to accelerator table
extern WORD g-- wOptions;
// automatic options
extern char g-- sIniFileName[ ];
// HDST init file pathname
Public Interface:
int PASCAL WinMain(
// program entry point
HANDLE hInstance, // handle to this program
instance
HANDLE hPrevInstance,
// handle to prev program
instance
LPSTR lpCmdLine,  // command line string
int nCmdShow);    // how to initially display
program
long FAR PASCAL AW-- WndProc(
// message processor for
main window
HWND hWnd,        // handle to window getting
message
unsigned message, // message being sent
WORD wParam,      // information about message
LONG 1Param);     // more information about
message
Windows Main Events:
#define IDM-- SRVCSETUP
1001   // services menu
items
#define IDM-- SRVCSENDFILE
1002
#define IDM-- SRVCSENDMSG
1003
#define IDM-- SRVCCHATMODE
1004
#define IDM-- SRVCDEBUG
1005
#define IDM-- SRVCEXIT
1006
#define IDM-- SRVCSENDSCREEN
1007
#define IDM-- SRVCVOICE
1008
#define IDM-- OPTSAUTOANS
2001   // options menu
items
#define IDM-- OPTSAUTORCV
2002
#define IDM-- OPTSRTNRCPT
2003
#define IDM-- OPTSDENYMSG
2004
#define IDM-- OPTSDENYCHAT
2005
#define IDM-- OPTSSAVE
2006
#define IDM-- WINDCASC
3001   // window menu
items
#define IDM-- WINDTILE
3002
#define IDM-- WINDARNG
3003
#define IDM-- WINDCHILD
3100   // id of first child
window
#define IDM-- HELPHELP
4001   // help menu
items
#define IDM-- HELPINDEX
4002
#define IDM-- HELPABOUT
4003
#define IDM-- INITISDN
5001   // internal mess-
age ids
______________________________________

ISDN Interface (AI) Module

Purpose:

The AI module serves to provide access to all necessary ISDN functions from the application.

Description:

This module provides all the needed functions so that the HSDT software may accomplish any task that requires ISDN activity. It includes a function which will be called from the Resource Management Layer 70 to deliver information about ISDN activity.

______________________________________
Data Structures:
extern RAT-- ApHan g-- hAppHnd;
// RA Layer application
handle
Public Interface:
BOOL AI-- Setup(
// Setup ISDN stuff
int iNumCards,
// number of ISDN BRI cards
char *sPhones);
// phone number for each B channel
BOOL AI-- Cleanup(
// Cleanup ISDN stuff
void);       // no parameters
BOOL AI-- Event(
// Callback function for RA
WORD wParam);
// event to process
______________________________________

ISDN Interface Events

The detail of these messages processed from the network are included in the header file (e.g. RA.H).

Call Connection (AC) Module

Purpose:

The AC module serves to provide services for the user to establish and drop connections and to view the status of the current connections. Also, the module serves to process messages for connection-related events.

Description:

The user may at times wish to view the current status of all connections, as well as establish or terminate. This module provides functions to allow the user to see and manipulate this information. It also keeps track of connection activity messages from the network to keep the display to the user current.

______________________________________
Data Structures:
struct ACS-- COON-- DATA
//Information for a connection
window
int  iNnDdIdx;  // current names and numbers
database index
HWND hActCtrl;  // handle of active child window
control
RAT-- CoHan xConnHdl;
// RA handle for this connection
HWND hXferWnd;  // handle to file transfer window
HWND hChatWnd;  // handle to chat window
HWND hClidBox;  // handle to call identification
group box
HWND hNumEdit;  // handle to number edit field
HWND hNameText; // handle to name text field
char szNum[DNC-- MAC-- NUM];
// stripped call identifi-
cation number
char szDNum[DNC-- MAX-- NUM];
// stripped call D channel
prefix
char szBNum[DNC-- MAX-- NUM];
// stripped call B channel
prefix
HWND hChanBox;  // handle to channel information
group box
HWND hAllBtn;   // handle to all channels button
HWND hOnlyBtn;  // handle to only use button
HWND hOnlyFld;  // handle to number of channels
edit field
int iChans;     // how many channels to use
HWND hStatBox;  // handle to status message group
box
HWND hStatText; // handle to status message
HWND hConnBtn;  // handle to connect button
HWND hDiscBtn;  // handle to disconnect button
HWND hAcptBtn;  // handle to accept button
HWND hRejtBtn;  // handle to reject button
HWND hDdirBtn;  // handle to dialing directory
button
HWND hCancBtn;  // handle to cancel button
Public interface:
long FAR PASCAL AC-- WndProc(
// message processor for
connect window
HWND hWnd,  // handle to window getting
message
unsigned message,
// message being sent
WORD wParam,
// information about message
LONG 1Param);
// more information about
message
int AC-- Setup(
// Setup a connection, return
handle
int iNumCards,
// number of ISDN BRI cards
char *sPhones);
// phone number for each B
channel
int AC-- GetStats(
// Get statistics on a connection
int iHandle,
// connection handle
WORD WParam);
// information on connection
BOOL AC-- Event(
// Callback function for RA
WORD wParam);
// event to process
______________________________________

Call Connection Events

The details of these messages processed from network are included in a header file (e.g. RA.H). Also included are messages processed from user, such as Accept, Deny, Request, etc.

File Transfer (AF) Module

Purpose:

The AF module serves to provide services for transmitting files to a subscriber station and receiving files from other subscriber stations. The module also serves to process file transfer-related messages.

Description:

The primary activity once a connection is established is to transmit a file from one station to another. This module provides access to the send file services.

______________________________________
Dat Structures:
struct AFS-- XFER-- INFO
// Information about a file
transfer process
int      iStatus;    // Transfer status
HWND     hConnWnd;   // Connection Window
RAT-- CoHan
xConnHdl;   // RA layer connection
long     1XferTicks; // Time to transfer file
long     1ElapsedTicks;
// Time so far
long     1Rate;      // On-going xfer rate
int      iBandWidth; // Number of channels
long     1FileLen;   // Total length of file
long     1BytesSoFar;
// Length of file sent so far
HWND     hTinfoBox;  // Handles on windows boxes/
text/buttons
HWND     hFinfoBox;
HWND     hStatBox;
HWND     hStatText;
HWND     hAbortBtn;
HWND     hStartBtn;
SFT-- FHan
hXferHdl;   // Service layer handle
};
Public Interface:
long FAR PASCAL AF-- WndProc(
// message processor for
file xfer window
HWND hWnd,  // handle to window getting
message
unsigned message,
// message being sent
WORD wParam,
// information about message
LONG 1Param);
// more information about
message
BOOL AF-- Event(
// Callback function for SF
WORD wParam);
// event to process
______________________________________

File Transfer Events

Messages processed from network--see RA.H for these messages.

Messages processed from user: OK, Cancel, Abort, Open, etc.

Messaging (AM) Module

Purpose:

The AM module serves to provide services for transmitting messages to another node and receiving messages from other nodes.

Description:

This module provides all functions and processing of user-to-user messages.

______________________________________
Public Interfaces:
long FAR PASCAL AM-- WndProc(
// message processor for
messaging window
HWND hWnd,  // handle to window getting
message
unsigned message,
// message being sent
WORD wParam,
// information about message
LONG 1Param);
// more information about
message
BOOL AM-- Send(
// Send a message
char *sMsg);
// message to send
BOOL AM-- Recv(
// A message has been received
char *sMsg);
// message received
______________________________________

Events

Details of the messages processed from network are included in a header file (e.g. RA.H). Also included are messages processed from user such as Send, Cancel, Close, etc.

Voice control (AV) Module

Purpose:

The AV module performs voice functions.

Description:

This service must allow for establishment of a call (either initiated using a phone number, or in intercepting and acknowledging an incoming call indication) and allow ISDN type keys to be delivered t the ISDN switch during the source of this call. It should also inform the application of incoming call indications, along with the calling number ID. This could augment the release of an appropriate `B` channel by the HSDT software so that the incoming call can be accepted.

______________________________________
Data Structures:
/*  information structure for the phone window
*/
typedef struct
WND hActCtrl;  /* child window control handle
*/
AT-- CoHan xConnHdl;
/* RA handle for this connection
*/
WND hNumEdit;  /* handle to number edit field
*/
WND hNameText; /* handle to name text field
*/
char xzNum[DNC-- MAX];
/* stripped call ID number
*/
WND hStatText; /* handle to status message
*/
WND hHoldBtn;  /* handle to hold button
*/
WND hDropBtn;  /* handle to drop button
*/
WND hTrnsBtn;  /* handle to transfer button
*/
WND hConfBtn;  /* handle to conference button
*/
WND hDdirBtn;  /* dialing dir button handle
*/
} AVS-- CONN-- DATA;
Public Interface:
long FAR PASCAL
/* for phone window messages
*/
AV-- WndPrc(
HWND hWnd,     /* wind handle getting message
*/
WORD message,  /* message being sent
*/
WORD wParam,   /* information about message
*/
LONG 1Param);  /* information about message
*/
HWND AV-- Setup(
/* Set up a new connection
*/
int SetupType);
/* reason for phone window
*/
setup
void AV-- Cleanup(
/* Destroy a phone connection
*/
HWND hWnd);    /* handle to phone window
*/
BOOL AV-- Event(
/* Callback function for RA
*/
WORD wParam);  /* event to process */
Voice Events:
Details of these messages are included in a header file (e.g. VX.H)
and include all messages of the format VXM-- Vxxx, where
"xxx" are alphanumeric characters.
______________________________________

It is understood, of course, that while the form of the invention herein shown and described constitutes the preferred embodiment of the invention, it is not intended to illustrate all possible forms thereof. It will also be understood that the words used are words of description rather than limitation, and that various changes may be made without departing from the spirit and scope of the invention disclosed.

Claims

1. A method for maintaining a plurality of isdn circuit-switched channels in an isdn, including at least one physical interface, used for performing various communication tasks including transferring isdn data between subscriber stations, each of the channels having a known bandwidth, where at least one of the subscriber stations includes a computer having an internal bus and at least one isdn terminal adaptor for coupling the channels to the internal bus, the method comprising the steps of:

linking several of the plurality of channels into a single logical connection;

synchronizing the channels of said single logical connection to permit the isdn data to be transferred to a second subscriber station at a first rate greater than the rate available on any one of the linked isdn circuit-switched channels; and

inputting selection data to the computer representative of a desired communication bandwidth, said selection data being utilized during said step of linking to link the several of the plurality of channels into said single logical connection.

2. The method as claimed in claim 1 wherein said step of linking includes the step of logically matching the channels of the at least one subscriber station to the channels of the second subscriber station, to support the step of synchronizing.

3. The method as claimed in claim 1 wherein said step of synchronizing includes the step of segmenting the data based on the bandwidth of each of the channels of the single logical connection to obtain segmented data.

4. The method as claimed in claim 3 further comprising the step of simultaneously transferring the segmented data on the channels of the logical connection to the second subscriber station in the network at the channels' respective data rates.

5. The method as claimed in claim 1 further comprising the step of modifying the single logical connection to obtain a modified logical connection, the step of modifying including the step of synchronizing the channels of the modified logical connection to permit isdn data to be transferred at a second rate different from the first rate.

6. The method as claimed in claim 5 wherein said step of modifying includes the step of releasing one of the channels of the single logical connection and linking the remainder of the channels into the modified logical connection.

7. The method as claimed in claim 6 wherein said step of modifying includes the step of releasing one of the channels of the single logical connection and linking the remainder of the channels and at least one other channel into the modified logical connection.

8. The method as claimed in claim 6 wherein said step of modifying includes linking the channels and at least one other channel into the modified logical connection.

9. The method as claimed in claim 1 further comprising the step of transferring files including data over the single logical connection to the second subscriber station in the network, the step of transferring utilizing substantially the total bandwidth of the channels of the single logical connection.

10. The method as claimed in claim 9 further comprising the step of transferring messages over the single logical connection to the second subscriber station in the network.

11. The method as claimed in claim 1 or claim 9 or claim 10 wherein a telephone is coupled to the at least one terminal adapter, one of the channels not associated with the single logical connection being coupled to the internal bus by the terminal adapter to provide a voice connection between the at least one subscriber station and a destination having a voice telephone, such as the second subscriber station.

12. The method as claimed in claim 1 wherein two of the channels of the single logical connection form at least part of separate isdn physical interfaces.

13. The method as claimed in claim 1 wherein two of the channels of the single logical connection form at least part of the same isdn physical interface.

14. The method as claimed in claim 1 wherein the single logical connection is formed utilizing channels from a plurality of physical interfaces.

15. The method of claim 1 wherein the computer is a personal computer.

16. The method of claim 5 or claim 9 wherein the data appears to a user to be transferred as a single bit stream.

17. The method as claimed in claim 1 or claim 10 further comprising the step of receiving a file including data over the single logical connection from the second subscriber station in the network to obtain a received file.

18. The method as claimed in claim 17 further comprising the step of storing the received file.

19. The method as claimed in claim 1 further comprising the step of receiving a message over the single logical connection from the second subscriber station in the network to obtain a received message.

20. The method as claimed in claim 19 further comprising the step of displaying the received message.

21. The method as claimed in claim 1 further comprising the steps of storing a directory of names and a number of associated destination numbers corresponding to a like number of subscriber stations and utilizing one of the destination numbers during the step of linking.

22. In an isdn system for performing various communication tasks including transferring isdn data between subscriber stations over a plurality of isdn circuit-switched channels, each of the channels having a known bandwidth, at least one of the subscriber stations including apparatus comprising:

a computer having an internal bus and at least one isdn terminal adapter for coupling the channels to the internal bus;

linking means associated with the computer for linking several of the plurality of channels into a single logical connection;

synchronizing means associated with the computer for synchronizing the channels of the single logical connection to permit the isdn data to be transferred to a second subscriber station at a first rate greater than the rate available on any one of the linked isdn circuit-switched channels; and

data input means associated with the computer for inputting selection data to the computer representative of a desired communication bandwidth, said linking means being responsive to said selection data for linking the several of the plurality of channels into the single logical connection.

23. The apparatus as claimed in claim 22 wherein said linking means includes means for logically matching the channels of the at least one subscriber station to the channels of the second subscriber station, to support the step of synchronizing.

24. The apparatus as claimed in claim 22 wherein said synchronizing means includes segmenting means for segmenting the isdn data based on the bandwidth of each of the channels of the single logical connection to obtain segmented isdn data.

25. The apparatus as claimed in claim 24 further comprising first means for simultaneously transferring the segmented isdn data on the channels of the logical connection to the second subscriber station in the network at the channels' respective data rates.

26. The apparatus as claimed in claim 22 further comprising means for modifying the single logical connection to obtain a modified logical connection, said synchronizing means synchronizing the channels of the modified logical connection to permit isdn data to be transferred at a second rate different from the first rate.

27. The apparatus as claimed in claim 26 wherein said means for modifying includes release means for releasing one of the channels of the single logical connection, said link means linking the remainder of the channels into the modified logical connection.

28. The apparatus as claimed in claim 26 wherein said means for modifying includes release means for releasing one of the channels of the single logical connection, said linking means linking the remainder of the channels and at least one other channel into the modified logical connection.

29. The apparatus as claimed in claim 26 wherein said means for modifying includes said linking means for linking the channels and at least one other channel into the modified logical connection.

30. The apparatus as claimed in claim 22 further comprising first means for transferring files including isdn data over the channels of the single logical connection to the second subscriber station in the network, the first means for transferring utilizing substantially the total bandwidth of the channels of the single logical connection.

31. The apparatus as claimed in claim 30 further comprising second means for transferring messages over the single logical connection to the second subscriber station in the network.

32. The apparatus as claimed in claim 22 or claim 30 or claim 31 further comprising a telephone coupled to the at least one terminal adapter, one of the channels of the single logical connection being coupled to the internal bus by the terminal adapter to provide a voice connection between the at least one subscriber station and a destination having a voice telephone, such as the second subscriber station.

33. The apparatus as claimed in claim 22 wherein two of the channels of the single logical connection form at least part of separate isdn physical interfaces.

34. The apparatus as claimed in claim 22 wherein two of the channels of the single logical connection form at least part of the same isdn physical interface.

35. The apparatus as claimed in claim 22 wherein the single logical connection is formed utilizing channels from a plurality of physical interfaces.

36. The apparatus of claim 22 wherein the computer is a personal computer.

37. The apparatus of claim 23 or claim 30 wherein the transfer of isdn data appears to a user to occur as a single bit stream.

38. The apparatus as claimed in claim 22 or claim 30 further comprising first means for receiving a file including isdn data over at least one of the channels of the single logical connection from the second subscriber station in the network to obtain a received file.

39. The apparatus as claimed in claim 38 further comprising a storage until coupled to the first means for receiving and storing the received file.

40. The apparatus as claimed in claim 22 or claim 31 further comprising second means for receiving a message over the single logical connection from the second subscriber station in the network to obtain a received message.

41. The apparatus as claimed in claim 40 further comprising a video monitor coupled to the second means for receiving and displaying the received message.

42. The apparatus as claimed in claim 22 further comprising a directory of names and a number of associated destination numbers corresponding to a like number of subscriber stations, the linking means utilizing one of the destination number for transferring the isdn data.

43. In an isdn system for performing various communication tasks including transferring isdn data between first and second subscriber stations over a plurality of isdn circuit-switched channels, each of the channels having a known bandwidth, each of the first and second subscriber stations including apparatus comprising:

a computer having an internal bus and at least one isdn terminal adapter for coupling the channels to the internal bus;

linking means associated with the computer for linking several of the plurality of channels into a single logical connection;

synchronizing means associated with the computer for synchronizing the channels of the single logical connection to permit the isdn data to be transferred between the first and second stations at a rate greater than the rate available on any one of the linked isdn circuit-switched channels; and

data input means associated with the computer for inputting selection data to the computer representative of a desired communication bandwidth, said link means being responsive to said selection data for linking the several of the plurality of channels into the single logical connection.

44. The method as claimed in claim 12 further comprising the step of receiving a message over the single logical connection from the second subscriber station in the network to obtain a received message.

45. The method as claimed in claim 44 further comprising the step of displaying the received message.